Gordon MacRae, the singer and actor who starred in the film versions of Richard Rodgers and Oscar Hammerstein 2d's benchmark musicals ''Oklahoma!'' and ''Carousel,'' died yesterday at Bryan Memorial Hospital in Lincoln, Neb. He was 64 years old and lived in Lincoln.

Mr. MacRae had been undergoing treatment for cancer of the mouth and jaw as well as pneumonia.

His 1955 performance as a robust cowboy in ''Oklahoma!'' was acclaimed by Bosley Crowther of The New York Times as ''wonderfully relaxed and unaffected.'' The critic praised Mr. MacRae's portrayal of a swaggering carnival barker in the 1956 fantasy ''Carousel'' as ''most attractive.''

The tall, athletic actor-singer made four genial, old-fashioned musical films with Doris Day - ''Tea for Two'' (1950), ''The West Point Story'' (1950), ''On Moonlight Bay'' (1951) and ''By the Light of the Silvery Moon'' (1953). Their teamwork prompted Thomas H. Pryor of The Times to conclude that ''these two complement each other like peanut butter and jelly.''

Other MacRae movies included a 1953 remake of Sigmund Romberg's ''Desert Song,'' co-starring Kathryn Grayson; ''Three Sailors and a Girl'' (1953), with Jane Powell, and ''The Best Things in Life Are Free'' (1956), co-starring Sheree North, in which Mr. MacRae played the Tin Pan Alley composer-lyricist Buddy DeSylva. A Self-Taught Actor

Mr. MacRae, who was self-taught in both singing and acting, lent his rousing baritone voice, clean-cut good looks, and boy-next-door personality to 16 movies. But in the mid-1950's, audiences' interest in musicals waned, and he got no more good offers.

He returned to television, where he had been a singing host and master of ceremonies on a series of programs, including ''The Railroad Hour'' and the ''Colgate Comedy Hour.'' Philosophic about the end of his movie career, he remarked in 1956: ''What counts is that what you're doing, you're doing well; that you're happy in what you're doing and it's not a chore. Nothing that you like is hard.''

The performer was the host of television's live ''Gordon MacRae Show'' in 1956, starred in a string of book-musical broadcasts and was one of the first popular singers to appear on the ''Voice of Firestone'' program. For decades, on radio and television, the show had featured only opera singers.

Mr. MacRae starred in national tours of musicals and in summer stock, and for nearly a decade he and his wife, Sheila, performed in nightclubs, on television and in concerts from coast to coast. They both sang, and she did satiric impersonations of show business figures. Starred With Four Children

In 1961, the MacRaes starred in a summer-stock version in Kansas City of ''Annie Get Your Gun'' with their four children - Meredith, Heather, Garr and Bruce.

Gordon MacRae was born March 12, 1921, in East Orange, N. J., to William Lamont MacRae, a toolmaker from Scotland who became a radio baritone in Syracuse, and the former Helen Violet Sonn, a concert pianist. The youth attended schools in Buffalo and Syracuse, played the piano and clarinet, spent spare time at lacrosse and football and was graduated from Deerfield Academy, where he sang in many shows.

At 19, he went to New York City and won an amateur singing contest at the 1939-40 World's Fair. This won him a two-week stint at the fair with the Harry James band. He became a page at NBC, was heard singing by a scout for Horace Heidt and sang with the Heidt band for two years. In World War II, he was a navigator in the Air Force.

After the war, Mr. MacRae resumed radio singing and gained a role as a military policemen in a 1946 Broadway revue, ''Three to Make Ready,'' starring Ray Bolger. The show drew mixed reviews, but Mr. MacRae's singing won him a movie contract with Warner Brothers. Returned to Broadway in 1967

He did not appear on Broadway again for 21 years, returning in 1967, when he and Carol Lawrence took over the roles originated by Robert Preston and Mary Martin in the musical ''I Do! I Do!'' and were praised by reviewers. In 1967, he and Sheila MacRae were divorced. Later that year, he married Elizabeth Lambert Schrafft.

In recent years, Mr. MacRae, acknowledging he was an alcoholic, made many public appearances on behalf of the National Council on Alcoholism. He had been the national honorary chairman of the council and a member of its board since 1983.

Surviving are his wife, Elizabeth, and five children - three daughters, Meredith, Heather and Amanda, and two sons, Garr and Bruce.

A memorial service is scheduled for Monday at 11:30 A.M. at the Sheridan Lutheran Church in Lincoln. In lieu of flowers, the family asked that contributions be given to the National Council on Alcoholism, 12 West 21st Street, New York, N.Y. 100l0.

Gordon Macrae (1921)