Main Prem Ki Diwani Hoon is based on the 1970's hit Chit Chor. A shy and reticent NRI tycoon, Prem Kumar (Abhishek Bachchan, who makes his entry only in the second half) is due to fly to India to finalise a deal and meet his prospective bride, Sanjana (Kareena Kapoor), a pouting, shouting, doubting Jane. Following a last-minute change in his plans, Prem's childhood pal, current employee and namesake, the gregarious Prem Kishen, a modern-day mix of Chit Chor's Amol Palekar and Geet Gata Chal's Sachin, makes the trip in his stead.

When the original Prem, a poetry-loving young man of few words, arrives on the scene with his doting mom (Reema Lagoo) and eccentric secretary (Johnny Lever), Sanjana's confused parents (Pankaj Kapur and Himani Shivpuri) are at their wit's end. The young lady is now too deeply in love with the first Prem to see the second Prem as anything more than a good friend. Copious tears are shed and emotional dam bursts are triggered as the girl's parents play the blame game and the heroine has to choose one Prem over the other.