Due to the Hays Code, much of the film had to be watered down from the 1931 version. The character of Ivy Peterson had to be changed from a prostitute to a barmaid.
Spencer Tracy originally wanted a realistic approach, whereby Dr. Jekyll would commit violent deeds in a neighborhood where he was unknown after drinking alcohol or taking drugs. He was disappointed that the producers, having bought the screenplay from Dr. Jekyll and Mr. Hyde (1931), insisted on virtually remaking the earlier film.
The film was a notorious critical failure when released, although it eventually made a profit of $2 million around the world. Spencer Tracy later said it was by far the least favorite of the films he had starred in, and that his performance was "awful". The New York Times famously described it as "not so much evil incarnate as ham rampant ... more ludicrous than dreadful."
One night Spencer Tracy turned up at Clark Gable and Carole Lombard's second wedding anniversary party wearing his make up as Mr. Hyde.
Despite having not yet met his famous co-star, Spencer Tracy wanted the characters of Ivy and Beatrix to be played by the same actress, Katharine Hepburn, to reinforce the theme of the good and bad qualities in every individual.