Raj Khanna (Rishi Kapoor) is a wealthy businessman who lives with his wife Archana (Rati Agnihotri), stepsister Devyani (Mita Vasisht), her spouse (Pramod Moutho), and her son Teddy (Mayur), in a mansion. Raj and Archana's lives are marred by marital discord, until they separate. Shortly before separating, Archana gives birth to identical twins: one of these is taken by Devyani and handed to Raj without Archana's knowledge. This infant becomes an embittered young woman sentimentally named Sweety (Kajol), and Raj becomes a helpless alcoholic. Archana has moved to London with the other daughter, Tina (Kajol). In contrast to Sweety's ferocity, Tina is meek, compassionate, sympathetic, and demure. Each year, Archana buys two identical presents, gives one to Tina on her birthday, and locks the other into a closet to symbolize giving to Sweety, whom she believes is dead.

Sweety is of marriageable age, but refuses to marry the man of her aunt's choice, and runs away to London. Once there, she is mistaken for her sister by Archana. Later, when the twins meet, they realize that Devyani has been scheming to keep Raj under her control, and change places in hope of freeing Raj and reuniting their family: each according to her own personality, but under the name of her sister. Tina goes to India to cure their father of alcoholism, while Sweety remains in England to acclimate their mother to her habits.

When Tina meets with Raj, she finds out that he is having a sexual affair with a young woman named Savitri (Pooja Batra), who was introduced to him by Devyani. When Savitri attempts to drug and seduce him, in hope of having him impregnate her (and so necessitate marriage), Tina gives the drug to Raj's aged, faithful, comical servant Ballu Mamaji (Razak Khan). Savitri becomes pregnant with Ballu Mamaji's child. Later, Sweety and Tina marry her off to a wealthy man they know (Parmeet Sethi). Ballu Mamaji attempts his own offer, but is refused. Through a series of tricks, the twins fool Raj and Archana into reconciling; Devyani's plots to gain power are exposed; and Raj, of his own will, urges Archana to stay.

• Sunil Shetty as Sameer
• Kajol as Tina / Sweety Khanna. Raj and Archana's daughters
• Rishi Kapoor as Raj Khanna
• Rati Agnihotri as Archana Khanna
• Mita Vasisht as Devyani (Raj's stepsister)
• Razzak Khan as Baloo
• Pooja Batra as Savitri
• Pramod Moutho as Devyani's lover (Doctor)
• Dinesh Hingoo as Sweety's Tina prospective father-in-law Anjana Ranjana Grandfather
• Parmeet Sethi Ranjeet uncle

• Aishwarya Rai Bachchan was considered for the role of Tina/Sweety.
• Rati Agnihotri returned to acting with this film after a 16-year break for marriage and motherhood.

The film soundtrack contains 8 songs composed by Anu Malik.