The Mad Doctor of Market Street is a 1942 American horror film produced by Universal Pictures starring Lionel Atwill. The film was a low-budget project that utilized the studio's contract players and gave rising director Joseph H. Lewis an opportunity to demonstrate his versatility with little production money.

The film is part of the mad scientist genre. In this case, the film's scientist performs regeneration experiments on human subjects. He survives a shipwreck and is stranded on a tropical island with the other survivors. He gains influence over the natives by demonstrating his ability to resurrect others, and uses that influence to get perform involuntary experiments on the other survivors.