Phagun is about Shanta(Waheeda Rahman), the daughter of a rich businessman and the wife of a poor writer. Her husband Gopal (Dharmendra) occassionally visits his wife who lives with her father. One day while playing Holi, the festival of colours, Gopal accidentally throws colour on Shanta and thereby spoils her expensive sari. Shanta harshly rebukes her husband. The humiliated husband walks out of her life.
In the meanwhile Shanta givens birth to a child. The child grows up to be a beautiful woman (Jaya Bhaduri) who marries a doctor called Suman. Suman is disturbed by the interference of his mother-in-law in their married life. Gopal soon becomes a famous writer and also a famous painter and he now buys some expensive saris for his wife Shanta to come back to her with. Unfortunately a fire destroys all the saris it and this shocks Gopal. Will Gopal and Shanta be re-united?