The idea for a Western adaptation of Japanese director Akira Kurosawa's 1954 classic The Seven Samurai came from Yul Brynner, though he could hardly claim to be the only one to see the story's possibilities. When Kurosawa's film was released in the U.S. as The Magnificent Seven in 1956, critics had described it as a Japanese Western. In fact, that was exactly what had been in Kurosawa's mind originally. He was a great fan of such American Western directors as John Ford and John Sturges (Gunfight at the O.K. Corral, 1957), who would eventually direct the American version of his story.

Brynner suggested the idea to Walter Mirisch, whose recently formed Mirisch Company was releasing films through United Artists. In search of the right film to put his company on the map, Mirisch picked up the rights.

Backing for The Magnificent Seven, which was budgeted at $2.5 million, came from two sources: The Mirisch Company, which had been releasing their films through United Artists since 1957, and a company Sturges had created with fellow directors Billy Wilder and Robert Wise.

Arguments over the rights to the film developed almost before the cameras even rolled. Anthony Quinn claimed that he had initiated the project and held the U.S. rights to the Japanese film. He also charged that ideas he had suggested to Brynner were in the shooting script. But he had nothing on paper, so the case was thrown out of court.

The next legal battle involved Lou Morheim of Brynner's production company, Alciona. He had been bumped from his position as producer when John Sturges was signed to direct and insisted on producing the film himself. Morheim claimed he deserved producer credit because of his work setting up the project. In particular, he had negotiated the re-make rights to The Seven Samurai from Toho Studios for just $250. Mirisch offered him ten weeks salary at $1,000 a week and 5 percent profit participation, but no credit. When he threatened a lawsuit, they gave in and gave him the credit.

Yul Brynner's son Rock was a fan of the television series Wanted Dead or Alive and reportedly suggested that his father cast its star, Steve McQueen, as his second-in-command, Vin. When the series' producers tried to pull him out of the film to shoot more episodes, McQueen crashed a rented car and claimed he had suffered whiplash. That put an end to the series, but he recovered in plenty of time to join the cast on location.

Days before production was to begin, the Screen Actors Guild threatened a strike and tried to close down the film. Fortunately, Mirisch had signed the U.S. cast members months before the strike vote, so the strike wouldn't effect production.