Pietro Lazzari, 80, a sculptor, painter, muralist and teacher whose works are in several major public collections in this country, died yesterday at the Bethesda Retirement and Nursing Center. He had a heart ailment and entered the center a month ago.

Mr. Lazzari, who had made Washington his home since 1942, worked in a variety of media - sumi ink on paper, oils, watercolors, bronze and concrete.

His polychrome concrete paintings, the style of which he originated, brought him fame. He became equally well known for his sculptures of such personalities as Pope Paul VI and Eleanor Roosevelt.

Some of his work became part of the permanent collections at the National Collection of Fine Arts and the Corcoran Gallery of Art here, the Art Institute of Chicago, the Metropolitan Museum of Art and the Whitney Museum of American Art in New York, the Miami Museum of Modern Art in Florida and the San Francisco Museum of Art in California.

His bronze bust of Eleanor Roosevelt, commissioned by friends of the former First Lady, is in the Franklin Delano Roosevelt Library in Hyde Park, N.Y. At the time it was accepted by then-President Lyndon B. Johnson in a ceremony at the White House in 1965, Mr. Lazzari noted:

"The art renaissance in America was born under the Roosevelt adminstration. The WPA (Works Progress Adminstration) and federal competitions sponsored by the Public Works of Art Project brought to artists in this country a new freedom and independence. I was part of this wonderrul renaissance, which let the artist create freely and be happy."

Mr. Lazzari had become part of the WPA art scene after he came to this country from his native Italy in the 1920s because, as he put it, "the fascists began mingling with the futurists."

He was born in Rome, not far from the Vatican, and studied as a master artist at the Ornamental School of Rome. He shared in the futurist movement with older artists such as Balla, Boccioni, Severini and Bragaglia.

While he was painting murals for the WPA in 1935, Mr. Lazzari developed concrete painting. Wet concrete accidentally spattered by paint caught his eye and led to his innovation.

He built a rough concrete coat over a wire mesh. He added another, smoother layer and, before the final layer dried, did his painting using pure pigment. He returned to Italy in 1950 on one of the first Fulbright grants for study abroad and researched ancient fresco techniques.

On another of his trip back to Italy, in 1966, he sat in on the weekly audiences of Pope Paul VI at the pope's summer villa at Castel Gandolfo outside of Rome and made sketches. He later had audiences with the pontiff and cast the bust on bronze.

Mr. Lazzari explained later that he decided to do the sculpture after watching Pope Paul VI's historic speech to the United Nations in 1965.

"I was very much taken with his [the pope's] plea for peace," the artist said. "I was in World War I for three years. I saw a lot of young soldiers die. I'm not a very religious person, but anyone who talks about peace, I'm with him."

That bust is at his Washington home. His bust of Socialist leader Norman Thomas is at the Eugene V. Debs Museum in Terre Haute, Ind., and that of statesman Adlai Stevenson at the United States Mission to the United Nations.

A bronze monument of Walter Reuther was installed at the Educational Center of the United Auto Workers at Black Lake, Mich. One of Mr. Lazzarihs works, a full-length bronze sculpture of Edward Miner Gallaudet, first president of Gallaudet College, stands on the campus of the noted college for the deaf here.

A year ago, to mark his 80th birthday on May 15, the International Monetary Fund art gallery opened a Lazzari retrospective of oils, polychrome concrete works and bronzes. At the same time, a retrospective of drawings also opened at the Franz Bader Gallery.

One of Mr. Lazzari's best-known bustsis of Bader, a friend since the artist's early days in Washington.

Perhaps Mr. Lazzari best expressed the drive that caused him to devote his life to art with these words at an exhibit in the 1960s:

"I try in my work to make Washington - to make the whole world - happy. There is so much suffering everywhere and in this country there is so much comfort that most of us forget those who are poor." He added that some of the money he got from sales at that exhibit would go to an orphanage in Rome.

Mr. Lazzari had taught at Dunbarton College, the Corcoran School of Art and American University. He was a member of the Washington Watercolor Society and the Artists Equity Association.

He is survive by his wife, the former Evelyn Cohen, of the home in Washington, and a daughter, Nina Maria, a graduate student at the Oregon College of Education in Monmouth, Ore. CAPTION: Picture, PIETRO LAZZARI