The MarxBrothers' seventh film, released in 1937 and following closely in the same mold as their previous one, ''Film/ANightAtTheOpera''.

Judy Standish's (Maureen O'Sullivan) sanitarium is under threat of being taken over by unscrupulous businessman J.D. Morgan (Douglass Dumbrille), who wants to demolish it and expand his real estate monopoly. The only hope for Judy is if she can keep as a permanent patient the wealthy hypochondriac Mrs. Upjohn (Margaret Dumont), who will only stay if the sanitarium hires her favourite physician, Dr. Hugo Z. Hackenbush (Groucho Marx). Unfortunately for Mrs. Upjohn, Hackenbush is actually a confidence-trickstering veterinarian, who has to avoid being caught out by either Morgan's cronies, the Florida Medical Board or Mrs. Upjohn.

Meanwhile, Chico Marx and Harpo Marx play a sanitarium worker and a former jockey who have to save Hackenbush from a FemmeFatale employed by Morgan, while simultaneously trying to get the racehorse owned by Judy's fiancée Gil (Allan Jones) into race-winning condition.

Not to be confused with the 1976 Music/{{Queen}} album ''Music/ADayAtTheRaces'', which was named after the movie.
!! In addition to the usual tropes exhibited by the MarxBrothers, this film provides examples of:

* AccidentalMisnaming: Chico keeps pronouncing Groucho's character Hackenbush's name as "Hackannapuss".
* CallBack: to ''Film/DuckSoup'' during the barn musical number, with the line "All God's children got swing." Previously it was "All God's children got ''guns.''"
* GrandeDame: Margaret Dumont again.
* InducedHypochondria: The reason Hackenbush is so well trusted by Mrs Upjohn:
-->'''Mrs Upjohn:''' Why, I never knew a thing was wrong with me before I met him.
* NonverbalMiscommunication: When Harpo tries to warn Chico about the frame job against Groucho. He gets it eventually.
* OneLiner
* RealJokeName: Averted, Groucho Marx's character was going to be Doctor '''Quack'''enbush, but MGM's Legal department heard from an actual Dr. Quackenbush complaining, so the name was changed to Hackenbush.
* SpiritualSuccessor: The basic plot is markedly similar to the previous MarxBrothers film, ''Film/ANightAtTheOpera'', except with horse-racing instead of opera.