This film marks the return of director Terence Fisher after an extended absence from Hammer productions, as his films were considered too slow and emotional by this point. Fisher has mentioned in multiple interviews (and by his daughter's admittance), that this film was his personal favourite to make, along with Horror of Dracula (1958). After directing this film and The Devil Rides Out (1968), Fisher would once again be out of the picture for a while due to several car accidents. His final Hammer film was Frankenstein and the Monster from Hell (1974).
Unlike his on screen persona, Veronica Carlson very much enjoyed working with Peter Cushing. At one point during production, he took his leading lady out to dinner with Mrs. Helen Cushing.
During filming, Peter Cushing and Veronica Carlson gave an on set interview. When the interviewer referred to Cushing making yet another "Hammer" horror film, the actor pretended to burst into tears and this created some laughter.
The fifth installment in Hammer Films' Frankenstein series.
The characters of Insp. Frisch (Thorley Walters) and the Police Doctor were added to the script at a late stage.