The casting started on 1 June 1964. Searching for the protagonist proved to be the most difficult. Leonid Gaidai looked for someone like himself and over 100 actors auditioned, including Oleg Vidov, Vsevolod Abdulov, Vitali Solomin, Evgeny Petrosyan, Sergey Nikonenko, Evgeniy Zharikov, Gennadi Korolkov, Ivan Bortnik, Valeriy Nosik (who appears in the movie in a smaller role), Aleksandr Zbruev and Andrey Mironov was in talks. The art committee recommended Nosik although Leonid Gaidai himself had doubts. After incidentally seeing a picture of Aleksandr Demyanenko, Gaidai left for Leningrad on 11 July for personal talks that proved to be successful. Demyanenko later said, "I realized the film was bound to be a success as soon as I read the script of 'Operatsiya Y'. No films like that were made in the USSR at the time."
The original script, approved for production on 25 March 1964, had the student named Vladik (Vladislav) Arkov and contained only the first segments, later entitled "Companion" and "Obsession". In the first segments, Vladik would 're-educate' a gloomy and ignorant person and in the second, would prepare a loony teen named Ilyusha (Ilya), an only child, for entrance exams required to join an institute. The two segments were not enough for a feature film. Leonid Gaidai had the idea to have Vladik meet the trio of Booby, Coward and Experienced from Bootleggers (1962) and this became the third segment, "Operation "Y", which gave the name to the whole movie.
The film was so enormously popular that it became the leader of Soviet film distribution in 1965 having 69.6 million viewers.
The film became a fountain of quotes for Soviet/Russian people. In spring 2012 a monument to Lida and Shurik reading the class notes over her shoulder was installed in front of the Kuban State Technological University, Krasnodar.
Segment "Obsession" was also edited into and black-and-white short film Operation 'Y' & Other Shurik's Adventures (1965), which was submitted to several film festivals and eventually won a Silver Dragon at Krakow Film Festival.