Synopsis :
Haseena Maan Jayegi is a story of two brothers, Sonu (Sanjay Dutt) and Monu (Govinda), sons of a wealthy man Amirchand (Kader Khan). The two brothers believe in living life in a carefree fashion as they know they will inherit their father's millions.

Amirchand is fed up with the tricks played by his two kaam chor sons to extract money from him. He does not want to give them money because they waste it every time.

Amirchand's secretary, Kunj Behari (Satish Kaushik), suggests that his boss separate the brothers to make them more responsible. Amirchand decides to send his son Sonu to Goa, to fetch money from a debtor and Monu to his office.

While in Goa, Sonu by mistake insults Gulzarilal (Anupam Kher), as he thinks him to be his father's debtor. Gulzarilal has a daughter, Pooja (Pooja Batra). Sonu, predictably, falls in love with her. Meanwhile, in Mumbai, Monu meets Ritu (Karishma Kapoor) and falls in love with her. But for a long time Sonu and Monu's respective love quest remains a one-way affair, as they are not able to win the hearts of their dream girls.

Finally Sonu is able to patao Pooja. But he has to convince Pooja's father Gulzarilal. Sonu gets Monu to help him by doubling in as Sonu's uncle.

Monu discovers that Ritu is actually the daughter of the same house he stays in. Monu believes it will now be easy to win Ritu's heart. He manages to do that but faces another problem. Girl's aunt Santosh (Aruna Irani) falls madly in love with him, believing him to be "Sonu's uncle". In the ultimate twist, Amirchand decides to go to Goa with his secretary and get his sons back. He meets his friend Gulzarilal while looking for his sons. In the end, all the confusion is cleared as everyone comes to know that Amirchand is Sonu and Monu's father, and he has no brother.