Sita (Meena Kumari) is married to Ram (Raaj Kumar), who is diagnosed to have cancer. Ram is admitted to a hospital where he is to be treated by Dr. Dharmesh (Rajendra Kumar). Dr. Dharmesh is Sita's former love and both of them are very much uncomfortable to interact in front of Sita's husband. Sita suspects that Dr. Dharmesh will not be able to give her husband a fair treatment because of his love interest in her. When she mentions this to him he promises her that he will try his best to save her husband. Ram overhears this conversation and later suggests to Sita that she should get married to Dr. Dharmesh after his death. Ram is to undergo a major surgery under Dr. Dharmesh, which will decide his fate. Dr. Dharmesh is seized with a feeling that he can't afford to fail in this surgery, as it might seem that he was biased due to Sita. He works hard for the preparation of the surgery, without proper food/sleep for a long time. Finally, at the end the surgery takes place. Dr. Dharmesh comes out from the operation theatre and tells Sita that the operation was successful and her husband is safe. He takes couple of steps forward and collapses. Long days of hard work for the preparation of surgery takes its toll, and he dies on the spot. The last scene shows Ram and Sita at the inauguration of a hospital built in Dr. Dharmesh's memory. Dr. Dharmesh's mother inaugurates his statue and everybody places flowers there.

• Rajendra Kumar – Dr. Dharmesh
• Meena Kumari – Sita
• Raaj Kumar – Ram^[2]
• Mehmood – Lallu Lal
• Kutty Padmini – Uma
• Shubha Khote – Mynavati
• Manmohan Krishna – Philip
• Achala Sachdev – Dharmesh's Mother

Dil Ek Mandir was directed by C. V. Sridhar and remade from his own Tamil film Nenjil Or Aalayam (1962). The entire film was completed in 27 days.^[2]

At the 11th Filmfare Awards, Raaj Kumar won the Best Supporting Actor Award and Arjun Dev Rashk won Best Dialogue.^[2]