The Strange Case of Doctor Rx is a 1942 black-and-white murder mystery/horror B film by Universal Studios directed by William Nigh and starring Patric Knowles, Lionel Atwill, Anne Gwynne, Ray "Crash" Corrigan and Samuel S.

The case involves a string of murders committed by someone calling himself Dr. Rx, and the victims are five clients whom Crispin had successfully defended in court.

However, he is kidnapped and blackmailed into continuing the investigation by a criminal whom the police suspect is the killer but who wants his name cleared when Church finds the real Dr. Rx.

[9] A New York Times review stated that the film was a "collection of babble clues, butlers at windows and gloomy manses, mysterious messages, stupid policemen, leers by Lionel Atwill and matrimonial badinage ... most of which is beside the point.

"[10] In their book Universal Horrors: The Studio's Classic Films, 1931–1946, authors Tom Weaver, Michael Brunas and John Brunas appreciated the on-screen chemistry between Gwynne and Knowles, but wrote that Atwill was wasted "in the reddest of red herring roles" and that Shemp Howard's bumbling cop routine fell flat.