Although Ann Blyth had done her own singing in her other movie musicals, her trained soprano voice was judged too operatic for the role of Helen Morgan, and pop singer Gogi Grant's voice was dubbed in. Ironically, the real Helen Morgan's light soprano voice was closer to Blyth's in quality than it was to Grant's. Ann Blyth revealed to writer-producer John Fricke that studio head Jack L. Warner had insisted on an intense, belting, Judy Garland-type sound for the film's Morgan.
The title role was declined by two actresses who had recently headlined successful biopics of troubled songstresses and didn't want to take on another such role: Doris Day (Ruth Etting in Les pièges de la passion (1955)), and Susan Hayward (Lillian Roth in Une femme en enfer (1955)).
This was Warner Bros. only feature in black-and-white CinemaScope.
Sammy White, who plays himself, appeared with the real Helen Morgan in three productions of "Show Boat"--the original 1927 Broadway stage production, the first Broadway revival in 1932, and the 1936 film version. White played the comic role of hoofer Frank Schultz in "Show Boat".
Singing stars Peggy Lee and Patti Page were both considered for the title role: Lee had co-starred in two movies, being recently Oscar-nominated for a troubled songstress turn in La peau d'un autre (1955) while Page's few cinematic forays were in the future. Also considered: lesser-known singers Helen Grayco, Peggy King, Micki Marlo, and Jaye P. Morgan; established singer/actress Julie London; veteran actresses Lizabeth Scott and Jennifer Jones; movie musical icons Judy Garland and Kathryn Grayson; and top model Nancy Berg.