Lee Krasner, 75, a major American painter who was a founder of the New York School and a pioneer of abstract expressionism died June 19 at New York Hospital where she was being treated for an intestinal ailment and acute arthritis. Miss Krasner was the widow of the legendary Jackson Pollock.

Art historian Barbara Rose has written that Miss Krasner was "one of the significant painters of the 20th century, an artist whose importance is only now beginning to be seen."

A serious painter since the early 1930s, Miss Krasner did not have her first solo show until 1951. Yet by 1965, a retrospective of her work at London's influential Whitechapel Gallery drew rave reviews and international recognition. Pictures in that exhibition were circulated by the Arts Council of Great Britain to museums in York, Nottingham and Manchester.

The first American retrospective of her work, a major art event, did not take place until October 1983 when it opened at the Houston Museum of Fine Arts. It later moved to San Francisco and is scheduled be displayed in New York City and the Pompidou Center in Paris.

In an interview with The Washington Post last year, Miss Krasner explained how she went about painting. "When I see a blank canvas, my preoccupation is with the entire surface of it. One goes between the curvilinear--those lush Venus-of-Willendorf curves, which Modrian spotted--and the horizontal and vertical. But I'm not conscious of a conflict there. You try to make as live a contact as you can, to bring that two-dimensional surface into vibration and life. You work with shapes and colors. Instead of my directing it, I let it happen. I'm concerned primarily with the area I'm trying to decorate . . . occupy."

A review in Artforum characterized some of her paintings in a 1973 exhibit at the Whitney Museum of American Art as "an unceasing flow of movement sustained by a nonhierarchical organization of line, shape and color." It went on to say that "all these works manifest an intensely personal, highly distinctive kind of handwriting--a calligraphy of the soul."

She was born Lenore Krassner in Brooklyn, N.Y., to Jewish immigrants from Odessa, Soviet Union. Her family owned and operated a small fish and vegetable store, and art was not high on the family menu. Miss Krasner once said that the only painting she could recall her family having was a portrait of Queen Isabella of Spain.

Miss Krasner began her voyage of discovery in high school, where she concentrated on art. She graduated from the Women's Art School of the Cooper Union Institute in 1929 then spent three years at the National Academy of Design. She also studied teaching at the City College of New York, and throughout these years held such jobs as waitress in Greenwich Village restaurants.

From 1937 to 1940, she worked in the studio of Hans Hofmann, and learned to share his passion for the works of Matisse, Picasso and Mondrian. She also joined the WPA Federal Art Project, where he colleagues included Gorky, de Kooning, Reinhardt, Stuart Davis and Pollock.

She and Pollock were married on Oct. 25, 1945. They left New York City and took up residence in an old farm at The Springs, a community in East Hampton, N.Y. The marriage was said to have been a difficult one, with problems that included a lack of money, Pollock's fondness for drink and the turbulent maturing of two artistic talents. In press interviews, Miss Krasner said that Pollock encouraged her work. The two artists shared the housework. They maintained separate studios, and each visited the other's workplace only upon invitation.

Pollock was killed in an auto accident in August 1956. If Miss Krasner had difficulty achieving success before Pollock's death, she found the world even more trying after it. Miss Krasner had always maintained that the art world was less liberated for women than most people would think. Critics and other artists looked upon her as "Mrs. Jackson Pollock" rather than an artist in her own right.

She also came under attack from some critics for what they perceived, through her control of the Jackson Pollock estate, as her role in the skyrocketing of prices for modern artworks. She said that this feeling against "Mrs. Pollock" was vented against artist Lee Krasner.

She maintained an apartment in New York City and the home in East Hampton until her death. Survivors include a sister, Ruth Stein of New York City.