Basil Rathbone as Sherlock Holmes

Nigel Bruce as Dr. John H. Watson

Gale Sondergaard as Adrea Spedding

Dennis Hoey as Insp. Lestrade

Vernon Downing as Norman Locke

Alec Craig as Radlik

Arthur Hohl as Adam Gilflower

Mary Gordon as Mrs. Hudson

Teddy Infuhr as Larry (uncredited)

Donald Stuart as Artie - Shooting Gallery Attendant (uncredited)

Harry Cording as Fred Garvin (uncredited)

Belle Mitchell as Fortune Teller (uncredited)

Angelo Rossitto as Obongo - Pygmy (uncredited)

Sylvia Andrew as Charwoman (uncredited)

Marie De Becker as Charwoman (uncredited)

Jimmy Aubrey as News Vendor (uncredited)

Brandon Beach as Carnival Patron (uncredited)

Frank Benson as Toy Doll Attendant (uncredited)

Lydia Bilbrook as Susan (uncredited)

John Burton as Radio Announcer (uncredited)

James Carlisle as Casino Patron (uncredited)

Jack Deery as Casino Patron (uncredited)

George Kirby as News Vendor (uncredited)

Stanley Logan as Robert (uncredited)

Wilbur Mack as Casino Patron (uncredited)

Edmund Mortimer as Casino Patron (uncredited)

William H. O'Brien as Doorman (uncredited)

John Roche as Casino Croupier (uncredited)

Gene Roth as Henchman Taylor (uncredited)

Arthur Stenning as Plainclothesman (uncredited)

Florence Wix as Casino Patron (uncredited)

Herschel Graham as Casino Patron (uncredited)

Ethelreda Leopold as Casino Patron (uncredited)