Opening credits: With ideas stolen from Robert Louis Stevenson.
This is the first of three Hammer adaptations of Robert Louis Stevenson's novella "Strange Case of Dr Jekyll and Mr Hyde". The other two are The Two Faces of Dr. Jekyll (1960) and Dr Jekyll & Sister Hyde (1971).
In this version, the family name is spelled"Jeckle".
The change sequence uses James Bernard's theme to "Dracula"