This Frankenstein film stands alone and is not a part of Hammer's six film Frankenstein series, starring Peter Cushing as Dr. Frankenstein. It was, essentially a remake of The Curse of Frankenstein (1957), and it is rumored that a younger actor, Ralph Bates, was cast to appeal to a younger audience.
Writer / producer / director Jimmy Sangster was brought in to look at and revise if necessary the original screenplay by Jeremy Burnham, and realized that it was essentially The Curse of Frankenstein (1957) all over again, which had been done just a dozen years earlier. Not wanting to do the same movie again, it was his decision to inject all the humor and sex into the script. He didn't commit fully to the project until Hammer Studios agreed to give him the opportunity to direct.