Trailblazer Althea Gibson, the first black tennis player to win the Wimbledon and US national championships, died on Sunday of respiratory failure. She was 76.

Gibson, who dominated women's tennis in the late 1950s and is a member of the International Tennis Hall of Fame, had been seriously ill for some years. She entered East Orange General Hospital, New Jersey, two days ago, said Fran Clayton Gray, her friend and cofounder of The Althea Gibson Foundation.

Gibson, born to sharecroppers on a cotton farm in South Carolina and raised in Harlem, became the first American black to play in the US championships in 1950 after posting a string of titles in the all-black American Tennis Association.

She broke the racial barrier at Wimbledon in 1951. Five years later, the tall, powerful right-hander became the first black woman to win a major tennis crown by taking the French championships title.

That triumph set the stage for a brilliant two-year run.

In 1957, Gibson became the first black to win the Wimbledon women's singles title and she repeated the feat by claiming the US national crown at Forest Hills.

"Her contribution to the civil rights movement was done with her tennis racket," said Gray, who will continue to run the foundation dedicated to the development of urban youth.

Her triumphs made her a national heroine. After her victory at Wimbledon, she was given a ticker-tape parade in New York.

Gibson dominated the next season as well, again sweeping Wimbledon and the US championship titles in 1958. She retired from the amateur ranks in tennis after the 1958 season. In all, she won 11 major tennis titles in singles and doubles.

There was no professional women's tennis circuit at the time, so Gibson parlayed her great amateur success into a lucrative series of exhibition tennis matches, preceding Harlem Globetrotters basketball games.

She then turned her athletic skills to golf and in 1964 became the first black to join the Ladies Professional Golf Association tour. She failed to win at golf, though, and quit the tour in 1971.

Gibson went on to become New Jersey state commissioner of athletics in 1975, a position she held for a decade.

Gray said Gibson suffered a heart attack a few months ago and had been bedridden since. "She was tired and weary. She was ready to throw in the towel," said Gray, who knew Gibson for more than 30 years.

Gibson's legacy as a pioneering black woman in sports was appreciated recently by Venus Williams, who along with her sister, Serena, became the first black women to triumph at Wimbledon and the US championships since Gibson's day.

"I knew she was watching when Serena won the US Open and she's happy to see another black woman win in her lifetime," Venus said after winning the 2000 US Open, one year after her sister had followed Gibson's example by winning the 1999 Open.