Munnabhai MBBS is based on Murli Prasad Sharma who is a local goon in Mumbai popularly known as 'Munna bhai'. He has kept his real identity secret from his parents, who think that their son is a doctor. Munna's parents arrive in Mumbai for their annual visit and his father meets an old acquaintance Dr. Asthana by chance.
They want to fix Munna's marriage with Dr. Asthana's daughter Suman "Chinky" Asthana. But Dr. Asthana comes to know about Munna's real identity, reveals it to his parents and humiliates them. Heartbroken, they leave for their hometown. Munna swears revenge upon Dr. Asthana and embarks upon getting an admission in a medical college to become a doctor.