Samuel Barber, 70 who died of cancer Friday in New York City, wrote beautiful music that was regularly performed by the world's greatest artists.

He was born on March 9, 1910, in West Chester, Pa. In his 70 years, he became one of the leading American composers of this century, standing with his friends and colleagues, Aaron Copland, Virgil Thomson, William Schuman and Gian Carlo Menotti, as representatives of much of the finest composition in the middle decades of the century.

Two of his finest works won him Pulitzer Prizes: his opera "Vanessa" that premiered at the Metropolitan Opera in 1958, and the piano concerto he wrote for the opening week of the Lincoln Center in 1962.

While Mr. Barber was still in his 20s, and only recently graduated from the Curtis Institute in Philadelphia, Arturo Toscanini conducted two of his compositions with the newly formed NBC Symphony Orchestra. The "Adagio for Strings," orignially the slow movement of Mr. Barber's only string quartet, was revised for full string orchestras around the world. For Toscanini he also wrote the first of three works for orchestra to which he gave the title "Essay." The third of these, which was one of Mr. Barber's last two compositions, had its world premiere only last season when Zubin Mehta conducted it with the New York Philharmonic, which also gave the first performance, in the same season, of Mr. Barber's last composition, an oboe concerto.

Mehta was the last in a long line of world-renowned conductors who found Mr. Barber's music very much to their liking and that of their audiences. Among those who regularly programmed his orchestral compositions were Bruno Walter, Serge Koussevitky, Eugene Ormandy, George Szell, Arthur Rodzinski, Leonard Bernstein, Dimitri Mitropoulos, Thomas Schippers and, recently Mstislav Rostropovich. Mitropoulos was the conductor the night the Metropolitan unveiled Mr. Barber's "Vanessa," which may very well be the most beautiful opera yet written by an American composer.

While it was Erich Leinsdorf who conducted the first performance of the Piano Concerto in Lincoln Center during the week of inaugural concerts in Philharmonic Hall, it was George Szell who took it on a European tour the following season, playing it frequently with John Browning as soloist.

Mr. Barber was one of the few American composers of his generation who was as completely comfortable writing for large and small instrumental combinations as for voices in various idioms. This stems from his musical background. He began studying the piano when he was six and started composing within another year or two. Entering the Curtis Institute at the age of 13, Mr. Barber studied piano with Isabelle Vengerova and voice with Emilio de Gogorza, a noted baritone of the time. His intense interest in songs and singing came from the fact that his aunt was Louise Homer, the most famous American contralto of her generation, an opera star who sang over 700 performances at the Metropolitan, usually in company with Enrico Caruso.

Mr. Barber once said, "I suppose it would be silly to deny that my musical impulses tend to correspond to what is generally meant by 'romantic.'" In the 50 years during which he wrote music regularly though not in vast quantities, this romantic quality was a principal factor in keeping his works before the public at a time when more controversial techniques were creating a considerable gap between many composers and music lovers.

Every musical honor came to Mr. Barber. In addition to his two Pulitzer Prizes, he won a Guggenheim Fellowship and a Priz de Rome. His First Symphony was the first American work ever to be performed at a Salzburg Festival. Commissions for new music came to him from Koussevitzky, the Metropolitan Opera and the Ford Foundation, from Elenor Steber and Martha Graham, the Air Force Symphony Orchestra, and from Eleanor Steber and Martha Graham, the Air Force Symphony Orchestra, and from Mary Curtis Zimbalist. It was for the latter that Mr. Barber wrote the stunning "Toccata Festiva" with which the new Aeolian-Skinner Organ in the Academy of Music in Philadelphia was dedicated. For Steber he wrote the hauntingly beautiful setting of James Agee's work, "Knoxville, Summer of 1915." For the Air Force Orchestra he wrote his Second Symphony.

Mr. Barber's piano sonata is in the repertoire of every good American pianist who can handle the technical hazards found on every page of a work which was given its world premiere by Vladimir Horowitz. Mr. Barber kept his own pianism in superb condition, displaying it on one historic occasion at the Library of Congress when he played for the youthful Leontyne Price in the premiere of his "Hermit Songs," in 1953.

One of his earliest works remains one of his most compelling: his setting of Matthew Arnold's poem, "Dover Beach," which Mr. Barber wrote when he was 21, scoring it for baritone and string quartet. By good fortune for Barber admirers, he made a recording of the work with the Curtis String Quartet. Recently reissued on New World 229, it illustrates the natural beauty of Mr. Barber's voice and his superb musicality.

His songs have been sung by hundreds of American singers as well as by Dietrich Fishcher-Dieskau and Pierre Bernac, for both of whom Mr. Barber wrote new music.

The one great disappointment of Mr. Barber's creative life was the almost universally negative reaction to his second large-scale opera, "Antony and Cleopatra," commissioned for the opening of the new Metropolitan House in 1966.The new opera was hopelessly buried at the start in an unbelievable overproduction by Franco Zeffirelli that cost close to a million dollars. But Mr. Barber agreed that certain revisions would improve the work, a view that was sustained two seasons ago when the Juilliard Opera Center's staging of the revised version won largely laudatory opinions.

Because of the inescapable sense of beauty that informs Mr. Barber's music and in the light of the current powerful wave of interest in music that speaks expressively to audiences on first hearing, it is likely that Mr. Barber's music, which exists in every idiom, will continue to win enthusiastic admirers for years to come, and that it will find permanent place among the finest music of this century.

There are no immediate survivors.