While filming, Ingrid Pitt and the girls had a great deal of trouble getting through scenes without giggling. In the scene where Ingrid has to drink from Kate O'Mara, her vampire teeth kept falling out and into Kate's cleavage. She eventually had to steal some gum from one of the stagehands to stick the fangs back in.

James Carreras rejected a suggestion that Bond girl Shirley Eaton play the lead on the grounds that she was too old. Ingrid Pitt, only 10 months younger than Eaton, was eventually cast.

Ingrid Pitt said in a 2009 column she wrote for Den of Geek that "When it came to the nude scenes, the director asked Madeline Smith and me if we wanted a closed set. It didn't bother me one way or the other because I've always been a bit of an exhibitionist so I had no problem letting people see me naked. Maddy Smith, being very British, was a little more nervous about prancing around in the nude. So we had a closed set. Producers Harry Fine and Michael Style were a bit peeved about this because they were barred from set too. They thought it was producer's perks to watch what was going on. Then one day I was walking to the set wearing just a dressing gown with nothing on underneath when I saw them coming in the opposite direction wearing a doleful look. As I went past them I open my dressing gown and said, Wheeeee! There was a spring in their step as they went on their way."

The director claimed that, after reading the novella Carmilla twice, he didn't get a sense of any lesbian content. Ingrid Pitt also claims she didn't play the role as though the vampire was a lesbian but asexual.

This film was given an R rating by the Motion Picture Association of America due to the vampire bites inflicted on the women's bosoms.

Peter Cushing was cast at a late stage.

Production began at Elstree Studios on 19 January 1970 and used locations in the grounds of Moor Park Mansion, Hertfordshire (standing in for Styria, Central Europe). Produced on a relatively low budget of £165,227, it was the final Hammer film to be financed with American money--most of the later films were backed by Rank or EMI.

The decapitation sound effect was achieved by cutting through a cabbage.

The role of the Man in Black was offered to Christopher Lee but he declined the role and John Forbes-Robertson was cast instead. Forbes-Robertson would also later replace Lee in Hammer's The Legend of the 7 Golden Vampires (1974).

The film takes place in 1790.

During an interview in 2000, Ingrid Pitt was asked if she was reluctant at all about her extensive nudity in this film. She replied: "I don't know about reluctant. I didn't think there was anything gross or indecent about what we were doing. I think Maddy Smith was probably a little more apprehensive than I was but I must salute [director Roy Ward Baker]. He gave us a closed set and treated it all as the most natural thing in the world. I do get people who seem embarassed when they buy nude photographs of me, They're very apologetic. I'm not sure why. It doesn't bother me. In fact I'm quite proud of the young bod. Something to show the grandchildren and remind them that Grandma wasn't always an old bag."

In 2009, Ingrid Pitt write about how she got cast for her role in her column for Den of Geek. She said one night after being in Where Eagles Dare, she went to a reception at the Savoy. "I was a bit disappointed to be seated next to a man I had never heard of. He introduced himself as James Carreras (the head of Hammer Studios at the time) and we chatted amicably while I kept a roving eye on the room in case there was anybody there I could impress. My attention was drawn back to Mr. Carreras when he started saying nice things about my part in Eagles. I am always susceptible to a little flattery. I agreed with him and asked him what he did. He told me that he was a film producer. That got my attention and by the time we left the party I had an appointment to meet him in his office the following morning to talk about a film he was about to produce." She said she was wary because she'd heard it all before and wasn't sure if she should trust him. But she showed up at the Hammer offices the next morning and he cast her for Vampire Lovers.

Mircalla Karnstein was born in 1522 and became a vampire in 1546.

Jon Finch's first film role.

Mircalla/Carmilla/Marcilla can walk in sunlight, casts a reflection in water but is repelled by a cross/crucifix and garlic.

Before production, the script was sent to the chief censor John Trevelyan, who warned the studio about depictions of lesbianism. They specifically wanted the scene of Kate O'Mara being seduced by Ingrid Pitt removed. They also pointed out that a previous lesbian film, The Killing of Sister George (1968), had had five minutes excised by his office. In response, Hammer replied that the lesbianism was not of their doing but was present in the original story by Le Fanu. Trevelyan finally backed down.

When asked about her sex scenes, Madeline Smith said "The one thing that was difficult for me was the lesbian aspect of it. I really couldn't be less lesbian than I am. I mean, I am totally disinterested in females. In that way, I really felt it was distasteful. I hated doing that, loathed doing it. Ingrid did too. THE VAMPIRE LOVERS was very steamy and I can remember Michael Style running around saying, 'The audience is going to fall asleep if you don't inject something in to it! At that time, I was still very innocent and I didn't know what to inject into it. I recounted my conversation with Derek Whitehurst, the film's assistant director, who told me that some of the crew members were a bit embarrassed by the nude scenes. "Oh, no, I think they enjoyed them!" laughed Smith. "I mean, there were these two lovely girls in bed. Why shouldn't they enjoy it? I think possibly Derek was a bit embarrassed. He's a good friend of mine, he lives just around the corner from me. He's the dearest, sweetest man you'd ever want to meet and he may have been embarrassed. I don't think the rest of the crew were."

The film was a co-production between Hammer and American International, who were interested in a vampire movie with more explicit sexual content to take advantage of a more relaxed censorship environment. It was decided to adapt Carmilla. Harry Fine and Michael Style were two the two producers.

The film was released on 26 August 2003 on DVD by MGM Home Video (Fox Video) as a double-sided Midnite Movies Double Feature DVD consisting of both The Vampire Lovers and Countess Dracula (1971). Scream Factory released the film on Blu-ray on 30 April 2013.

Ingrid Pitt was offered a role in the sequel - Lust For A Vampire (1971) - but she disliked the script and chose to star in Countess Dracula (1971) instead. This is the only film where she plays Carmilla Karnstein.

General von Spielsdorf is a joke name. Spielsdorf means "play village".

Ingrid Pitt was cast after producer James Carreras saw her in Where Eagles Dare (1968).

When filming the nude scene, a case of champagne was left on set - which Ingrid Pitt and Madeline Smith made their way through to put themselves at ease.

Kate O'Mara's work in The Vampire Lovers impressed Hammer enough for them to offer her a contract, which she turned down, fearful of being typecast.

Ingrid Pitt was asked during an interview what it was like working with director Roy Ward Baker. She replied he was "Patient and willing to work out any problems that might crop up without sounding irritable or giving the impression that it is a burden having to work with a load of dumb broads. Something that not a lot of directors are capable of doing and still keeping control."

In a 2013 interview with Film News, Madeline Smith was asked what it was like to work with Ingrid Pitt in 'The Vampire Lovers' and how she feels about the nude scenes when she sees them today. She said "Ingrid was a formidable lady, but was very solicitous to me, sensing my innocence and ignorance. I hated the nude scenes then and ever more so today. I was cajoled into removing my top and was reassured that it was only for the 'Japanese' market.'"

In her last interview published in 2013, Ingrid Pitt was asked why she thought the lesbian vampire is such a potent horror icon. She said "When I made The Vampire Lovers, it really didn't strike me that it was a lesbian-based story. I thought it was just about a couple of nubile girls in a grand house in a hot Styrian summer with nothing to do but play with each other. As far as I remember, both the victims had a boyfriend. The same one I think. It was just bad luck on him that their house guest turned out to be a rapacious female vampire. When a man plays the vampire, it's usually a matter of moving in on his victim, a pretty young girl, and wham, bam, thank you man. Female vampires are expected to wear the minimum of clothing and make sure that they catch the back lighting as much as possible. What they do wear must fall around them to reveal maximum flesh when they get down to business. I think the lure of the character is in its sexuality and the fact that double dibs are on tap if both the victim, naked and screaming, is molested before being sent into orgasm by a bite on the neck by a woman."

In an interview published in 2013, Ingrid Pitt was asked if she thought she and the other female actors were exploited in The Vampire Lovers since it had so much nudity. She said "How can you be exploited if you know what you are doing, have the opportunity of backing out, and are getting paid to do the job? I had a good body and had no inhibitions about flaunting it. There was nobody, off camera pointing a gun at my head. Maddy Smith wasn't too certain at first and we were given the chance to pull out at any time. As it turned out, we had fun doing the scenes and found the attitude behind the camera highly amusing. They were all frightened we might decide to give it a miss and made sure not to appear prurient. They treated us as if it was an everyday occurrence to have two fanciable female frolicking about in the all together."

Part of hammer Films and Tudor Gates' Karnstein trilogy of vampire movies based on Sheridan Le Fanu's novel Carmilla. The other two titles are Lust For A Vampire (1971) and Twins of Evil (1971).

Ingrid Pitt's first nude scene.

A Gathering of Vampires: Ferdy Mayne (Doctor) had previously played a vampire in The Fearless Vampire Killers (1967), then as a vampire named Fürst "Christopher" Dracula in German film The Vampire Happening (1971). John Forbes-Robson (Man in Black) later played Dracula in Hammer's Legend of the 7 Golden Vampires (1974) with Peter Cushing. And Peter Cushing, no stranger to vampire hunting, portrayed an actor playing a vampire in French film The Big Scare (1974), AKA Tender Dracula, in full Dracula costume.

Sherlock meets Holmes: Douglas Wilmer (Baron Hartog) and Peter Cushing (The General) both played Sherlock Holmes. Wilmer portrayed Holmes in the BBC television series The Adventures of Sherlock Holmes (1964 - 1965), then again in The Adventure of Sherlock Holmes' Smarter Brother (1975) with Gene Wilder. Cushing portrayed Holmes in Hammer Films Hound of the Baskervilles (1959), then took over the role in The Adventures of Sherlock Holmes in 1968, then lastly in the television movie Sherlock Holmes and the Masks of Death (1984).

Ingrid Pitt once said "There are extra perks in appearing nude on screen. Everybody gets very solicitous. In the bath scene the crew keep checking that the water is the right temperature. Are the lights too bright, are you comfortable with the people on set, would you like a cognac? They are all terrified that you are going to throw a wobbly and walk off."

Madeline Smith. who was 19 when she made the film, said that no one mentioned nudity when she auditioned and she didn't think to ask, even when she read the script which had her "larking about" with Ingrid Pitt in a bedroom. She said she was incredibly nervous when she found out about it because she had never been nude on screen before. But she agreed to dodo it because she didn't want to be fired. "When it came to the shoot the producer just took me to one side and said 'Don't worry this is for the Japanese version, no one will see it here'. We did film two versions of the bedroom scene but the only one they used was the topless one with me running about when you can see my bosoms jumping up and down." That's the version they used for all the releases. "I thought it was a shame because Hammer didn't need to inject the added sex. They were quite good enough and certainly plenty horrible enough."

According to Madeleine Smith, during the 1970s directors had no shame in leering over her figure in this and other films, but, the actress said in an interview years later that she didn't mind: "When I was a teenager I was anorexic and thoroughly miserable. I'd been on medication, which was one of the main reasons why I didn't take drugs at a time when they were rife in the business later on, so when I suddenly blossomed I was very happy to be voluptuous."

Italian censorship visa # 60251 delivered on 26 April 1972.