Karuna (Meena Kumari) comes to Dr. Malhotra’s Hospital to etch out a new life for her, leaving behind the pain of an orphan life. At the hospital she meets the respected Dr. Malhotra, a dominating head nurse, a fun loving colleague and an amagam of patients who all endear themselves to her quickly. Also working and living close to the hospital is Dr. Sushil (Raj Kumar), a respected surgeon. Through a minor accident involving Munni (Baby Naaz), Dr Sushil’s sister, Karuna quickly earns the love and respect of Dr. Sushil’s mother and family. Working closely with Dr. Sushil, Karuna slowly finds herself drawn to him and wishes for an even closer relationship, but fate would play a different role for her. While visiting Lalaji, an old family friend and his daughter Kusum (Nadira)in Kashmir, Dr Sushil is cajoled into marrying Kusum. Karuna is shocked to see Dr. Susheel, now a married man, but soon comes to terms with his bride amd new life. Kusum, a girl froma rich famliy finds it difficult to adjust to a new life with a virtuos Sushil awho puts servitude before his family life. Soon there is much discord in the household and Sushil and his mother realize that they were wrong in not considering Karuna for a bride. Dr Sushil soon finds himself falling for Karuna, and when Karuna realizes the extent to which Sushil has fallen in love with her, she decides to resign. Dr. Malhotra refuses her resignation and Karuna, Sushil and Kusum are forces to come to terms with their relationship. How each one reacts and/or decides to sacrifice their love for one another forms the crux of "Dil Apna Preet Parayee".