The film was scripted by
Sachin Bhowmick. The theme of the movie was based on the 1946 film
To Each His Own. A day prior to the shooting of
Aradhana, producer Surinder Kapoor showed Samanta his latest film,
Ek Shrimaan Ek Shrimati with
Shashi Kapoor as the lead, which was also written by Sachin Bhowmick. Much to his surprise, this film had a similar ending to his own film. The following day, Samanta decided to scrap his film, when writers
Gulshan Nanda and Madhusudan Kalelkar visited his office. Upon hearing the issue, it was Gulshan Nanda who suggested to have a double role of father and son in the film. Originally, the first hero was to die by the interval and a new hero was to step in. The same evening, while
Aradhana was being cancelled, Nanda recited a story of
Kati Patang to Samanta, which he instantly liked, so for the next couple of hours they first rewrote the second half of
Aradhana, and subsequently went on to discuss
Kati Patang.
Asha Parekh was the first choice for the role of Vandana. However, she rejected the offer, as she did not want to play Rajesh Khanna's mother in the film. She later played the lead role in
Kati Patang. The "Roop Tera Mastana" song sequence, which lasted more than three minutes and 30 seconds, was filmed in a single take. Sharmila Tagore believes this was done due to time constraints. Shakti Samanta reminisces in an interview that he suggested to Rajesh Khanna that he mimic
Dev Anand in his second role as a son. He did and it clicked. == Soundtrack ==