Max Brand's story was published as a novel in 1941. A HR news item during the film's production noted that USC football star Tony Beard was to portray a doctor in the picture, but his participation in the completed film has not been confirmed. Roger Converse is listed in the cast on a HR production chart, but he was not in the released film. News items also noted that Young Dr. Kildare was the first M-G-M picture to open at New York's Radio City Music Hall, and that Harry Bucquet was making his directing debut with the film. Bucquet had previously worked as an assistant director and second unit director at M-G-M for many years. At the end of the picture, actors Lew Ayres and Lionel Barrymore appear as themselves and announce to the audience that they will appear in "further adventures" of "Drs. Kildare" and "Gillespie." Barrymore, who is in a wheelchair, then quips that he is still in a wheelchair because of his role and thought that the audience would not recognize him without it. This was the first in a series of fifteen popular films set at Blair General Hospital in New York. Ayres appeared as "Dr. James Kildare" in the first nine films of the series, but left after completing Dr. Kildare's Victory in 1942. As the United States entered World War II, Ayres declared himself a conscientious objector and lost his popularity with fans. After being confined for a time with other conscientious objectors at Cascade Locks, Oregon, Ayres entered the U.S. Army Medical Corps. and served with distinction. In a modern interview, Ayres has stated that his role in the "Dr. Kildare" series influenced his decision to become a medic. Subsequent to the end of the war, Ayres returned to filmmaking, but his career never attained the status that it had previous to his unpopular decision not to serve as a fighting man.
       After Ayres left the series, several other actors portrayed "Dr. Gillespie's" assistants, but none took over the character of "James Kildare." The later films usually had "Dr. Gillespie's" name in the title, and the series became known as the "Dr. Gillespie" series, although many contemporary and modern sources refer to all of the films as "Dr. Kildare" pictures. Throughout the series, Barrymore, who was crippled by arthritis, acted in a wheelchair, a requirement of his physical condition rather than an affectation of his character. Of the successors to Ayres, Van Johnson and Keye Luke were the most popular, and appeared in several films in the early 1940s. The last film in the series was Dark Delusion (1947), starring James Craig, Keye Luke and Lionel Barrymore. In addition to "Drs. Kildare" and "Gillespie," most films in the series featured a number of recurring characters, among them Kildare's parents (Emma Dunn and Samuel S. Hinds), "Dr. Walter Carew," (Walter Kingsford) the chief administrator of the hospital, ambulance attendant "Joe Wayman," (Nat Pendleton) and switchboard operator "Sally" (Marie Blake). The second film in the series, Calling Dr. Kildare, released on 28 Apr 1939, introduced Laraine Day as "Nurse Mary Lamont," Dr. Kildare's love interest in several subsequent films, and Alma Kruger as "Molly Byrd," head of nurses, who became both friend and foil to Dr. Gillespie.
       The character of "Dr. James Kildare" was previously featured in the 1937 Paramount film Internes Can't Take Money. Joel McCrea portrayed "Kildare" in that film. The characters of "Kildare" and "Gillespie" were revived by M-G-M for a popular NBC television series, Dr. Kildare, which ran from 1961 to 1966. In the television series, Richard Chamberlain appeared as "Kildare" and Raymond Massey assumed the role of "Dr. Gillespie."