Ieoh Ming Pei, architect of the East Building of the National Gallery of Art and many other acclaimed buildings, yesterday was awarded the 1983 Pritzker Architecture Prize.

Pei was cited for having "given this century some of its most beautiful interior spaces and exterior forms" in a press conference at New York's Metropolitan Museum of Art.

The 66-year-old New York architect is the fifth recipient of the Pritzker Prize, which has become the most important international architecture award since it was established in 1979 "to reward a creative endeavor not honored by the Nobel Prizes." The winner receives $100,000 tax-free and a bronze sculpture by Henry Moore.

"Naturally, I'm very gratified by it," Pei said yesterday. "The fact that at last recognition is being given to the important role of architecture in our society--not me, architecture--is significant."

Among Pei's notable buildings, in addition to the East Building, are the recently completed Fragrant Hill Hotel in Peking; the West Wing of the Boston Museum of Fine Arts, completed in 1981; the John Fitzgerald Kennedy Library in Dorchester, Mass., 1979; the Dallas City Hall, 1977; the Everson Museum in Syracuse, N.Y., 1968; the National Center for Atmospheric Research in Boulder, Colo., 1967, and outstanding high-rise corporate office buildings in the United States and Singapore.

The six-member jury praised the range of Pei's work over four decades, "including not only palaces of industry, government and culture, but also some of the best moderate- and low-income housing." National Gallery of Art Director J. Carter Brown, who worked closely with Pei on the East Building, served on the jury, as did two former Pritzker laureates, Philip Johnson, who won in 1979, and Kevin Roche, last year's recipient. (Luis Barragan of Mexico received the award in 1980 and James Sterling of Great Britain in 1981.) The remaining jurors were Japanese architect Arata Isozaki; J. Irwin Miller, an architectural patron and officer of the Cummins Engine Co., and Thomas J. Watson, chairman emeritus of IBM.

Pei has characterized himself as an architectural conservative who has built upon the Modernist tradition. His varied buildings are typified by bold forms, geometrical daring and crisp clarity of layout. And, as the jury noted (and any visitor to the East Building can attest), he has "elevated the use of materials to an art."

Pei was born in 1917 in Canton, China, to a wealthy banking family. He came to the United States in 1935 to study engineering at the Massachusetts Institute of Technology. At the urging of William Emerson, his dean, he switched to architecture and received his bachelor's degree in that discipline in 1940. He then studied with Walter Gropius, Marcel Breuer, Philip Johnson and other International Style modernists at the Harvard Graduate School of Design, receiving his master's degree in 1946.

While teaching at Harvard the brilliant, persuasive young architect caught the attention of builder William Zeckendorf and in 1948 was appointed to the newly created post of director of architecture at Webb & Knapp Inc., Zeckendorf's company. He left that position to establish the firm of I.M. Pei & Partners in 1955.

Pei is credited with several important structures in Washington besides the East Building--the distinguished Christian Science Monitor Building and its related church at 16th and I streets NW (1972), the north and south office buildings at L'Enfant Plaza (1965), the William Slayton House with its triple arches at 3411 Ordway St. NW (1962) and the sleek Town Center Plaza apartment houses in the Southwest urban renewal area (1961-62).

Except for the Town Center Plaza buildings, his own role in these projects was limited, Pei said yesterday. Araldo Cossutta was the partner in charge of designing the Christian Science and L'Enfant Plaza buildings, he said, and Slayton himself (who was then a Webb & Knapp vice president) contributed greatly to the house design. "We did it on the backs of envelopes, traveling from city to city," Pei said.

But he was not at all reluctant to take credit for the East Building. "It has to be very important in my work," he said, "because of where it is. The challenge was there and the opportunity for failure was very great--so one couldn't afford to fail."