Paul Newman, Burt Lancaster, Max von Sydow, and Peter O’Toole were considered for the lead. Director David Lean wrote, “Zhivago has to be a sensitive but strong man; no popular idea of a long-haired dreaming poet and not the one-layer-deep action hero who knows where he's going and the difference between right and wrong.” The part was offered to O’Toole (whom Lean had worked with on Lawrence of Arabia) but due to commitments to other film projects, he had to decline. Instead, Omar Sharif, who also appeared in Lawrence, was cast.

Producer Carlo Ponti wanted to cast his wife at the time – Sophia Loren. However, director David Lean didn’t think she was right for the part and politely declined. Jane Fonda and Yvette Mimieux were also considered.

Lean wanted Audrey Hepburn for the part. However, producer Ponti requested that Geraldine Chaplin, daughter of Charlie Chaplin, be tested for the role. Lean was impressed by her performance and cast her instead.