Martine is looking for a way to take revenge on her husband Sganarelle, who just beat her up during a fight. Up come Valère and Lucas, who are looking for a doctor on behalf of their master Géronte. Seized by inspiration, Martine tells them that Sganarelle is exactly what they're looking for: a doctor so fantastic that he can cure death. She also tells them that Sganarelle is an eccentric, who won't admit that he's a doctor until he's been beaten up. Valère and Lucas follow her advice, and Sganarelle tells them that he's a doctor if that's what it takes to make them stop.
Sganarelle is then taken to Géronte, who explains to him that his daughter, Lucinde, has gone mute, and that, so far, nothing he's tried to get her to speak has worked. Lucinde's maid, Jacqueline (also Lucas's wife) remarks that if only Géronte gave her a husband she likes, Lucinde would have no trouble recovering speech. Sganarelle hits on Jacqueline and impresses Géronte by speaking Pig Latin to Lucinde. Later, he is approached by Léandre, Lucinde's lover, who asks for Sganarelle's help to elope with Lucinde. He offers Sganarelle money, and Sganarelle accepts.
Disguised as a pharmacist, Léandre is able to talk to Lucinde while Sganarelle distracts Géronte. Géronte, however, turns his head and sees Lucinde talking. Sganarelle then tells the young couple to run away. Lucas, still mad that Sganarelle hit on his wife, tells Géronte that Sganarelle was in on Lucinde's elopement, and Géronte takes out his wrath on the fake doctor. Then Léandre comes back with the news that his rich uncle has died and he's inherited his fortune. Géronte happily agrees to Lucinde and Léandre's wedding. Sganarelle is released and his healing powers go to his head, while Martine comes back to him, humbled by the thought of being married to such a wise and knowledgeable man.
The Doctor in Spite of Himself provides examples of:
- Author Appeal: A rich but naive bourgeois with a beautiful daughter. Ends with a wedding. The character is Played for Laughs and very often played by Molière himself.
- Domestic Abuse: The whole plot starts when Martine decides to get even with Sganarelle for beating her up.
- Deus ex Machina: Molière's comedies and farces are generally fond of this.
- Take That!: Doctors using Canis Latinicus. The rich (and poorly educated) bourgeois father pretending to understand it so as not to look stupid.
- Name's the Same: Sganarelle (the doctor) also appears in The Flying Doctor. A character named Sganarelle presumably not intended to be the same person also appears in plays as different as Dom Juan, Doctor Cupid, and the aptly-named Sganarelle or the Imaginary Cuckold, as a valet and a bourgeois. Interestingly, dressed the same in all of these plays, and always played by Molière himself.