Trivia

Christopher Lee's role as Paul Allen in the film was written especially for him and was one of his personal favorites.

This film adaptation of Robert Louis Stevenson's novella Strange Case of Dr. Jekyll and Mr. Hyde (1886) features the opposite in the transformation: the older and sensible Jekyll is mustached and bearded and speaks in a low voice while the younger and hedonistic Hyde is clean-shaven and speaks in a friendly-sounding voice.

Christopher Lee originally wanted to play the lead role(s) in the film.

At the time when the film was ready to be released, the BBFC were not very impressed with a few scenes in it involving sex and violence. They ordered that the snake dance scene, some brief glimpses of nudity and one of the murder scenes were all to be reduced in content.

This is the second of three Hammer film adaptations of Robert Louis Stevenson's novella Strange Case of Dr. Jekyll and Mr. Hyde (1886). The first one was The Ugly Duckling (1959) and the third and final one was Dr Jekyll & Sister Hyde (1971).