Munnabhai (Sanjay Dutt) is a local goon, who lives with his gang near a 'dhobi ghat' in Mumbai. Munna is an easygoing guy and he is happy with the way his life is going, till one day, when his life takes a turn.
Munna's father and mother arrive in Mumbai, on their annual visit. Munna's father, Hari Prasad Sharma (Sunil Dutt), is self respecting man, who believes that his son is actually a doctor running a charity hospital. Every year, when his parents arrive, Munna and his gang bathe, shave, don white coats and stethoscopes and pretend to be diligent doctors.
This year, however, the clever charade falls apart. Hari Prasad Sharma meets an old friend, Dr. Asthana (Boman Irani), who has a daughter called Suman (Gracy Singh). The two decide that their children, both doctors, would make a perfect match. Munna tries hard to save the situation, but his father discovers the truth. Needless to day, his father is heartbroken, and Munna decides to leave his ways and become a doctor.
Munnabhai MBBS is a hilarious and touching story about how a goon, enters the world of medicine and changes the same.