Arun is married to Leelavathi in a forced marriage. He is embarrassed by his wife's plain looks and her weight. When he meets Priya - who works in a building construction company, he hides from her the fact that he is married and has an affair with her. When he takes Priya with him on a vacation to Bangalore, he bumps into his old friend Dr. Sakthivel Gounder - an orthopedic surgeon from Coimbatore who is also in Bangalore with his wife Palani and his son Anand - travelling with him in the same flight and even staying in the same hotel. Sakthivel is called to Arun's room in the night - as Arun has slipped his disc and the hotel doctor is unavailable - and bumps into Priya, thus finding out about the affair. After returning to Chennai, Priya finds out that Arun is married, but decides to continue with him when Arun says he was forced into marriage and promises to divorce his wife. When Arun's wife Leelavathi discovers Arun's affair, she has a huge showdown which leads to Arun leaving the house. Then, Leelavathi plans a series of dramas which makes Priya hate Arun. She does this with the help of Sakthivel, her father-in-law, children and Priya's old lover. Finally Priya unites with her old lover apologizing to him and Arun unites with Leelavathi.
Magie was the art director, while Balu Mahendra was also editor and cinematographer for the film. Kovai Sarala was signed to portray the role of Palani after great debate. While Kamal Haasan wanted her in the film, Balu Mahendra was hesitant. Kamal Haasan waited for Sarala for six months and brought her on board the film. Sarala later said that Mahendra was delighted that she was part of the film and that he felt bad for initially having doubts in her ability. Kamal Haasan speaks Kongu Tamil in the film, which he was said to have learned from Kovai Sarala. Kovai Sarala won Tamil Nadu State Film Award for Best Comedian award.
The film became a profitable venture for the producers. The film was later remade in 1999 in Hindi by David Dhawan as Biwi No.1 with Salman Khan, Anil Kapoor and Sushmita Sen in pivotal roles. The film was later also adapted in Kannada by Ramesh Aravind in 2005 as Rama Shama Bhama, with Aravind and Kamal Haasan reprising their roles.
