Ostrowski's sister, Beth Hundman, says Ostrowski died Friday night in Bristol, Va. Hundman says her sister was diagnosed with multiple myeloma, a type of blood cancer, in 2007, and she died from complications from the illness.
While at Tennessee, Ostrowski helped the Lady Vols advance to NCAA Final Fours in 1981, 1982 and 1984. She was an SEC All-Tournament Team member and an All-SEC selection in 1982 and 1984.
Ostrowski ranks fifth in rebounds and 10th in points at Tennessee. She was inducted into the Lady Vols Hall of Fame in 2006.
A message expressing condolences was posted on former Tennessee coach Pat Summitt's Twitter account.
"Thinking of Mary O today. Love and prayers for her family. Once a Lady Vol, always a Lady Vol," the message said.
Ostrowski, a 6-foot-2 forward, also was a member of the United States team from 1981 to 1983. She earned a gold medal at the 1983 World University Games.
As a standout at Parkersburg Catholic High School in West Virginia, Ostrowski was the first female winner and a three-time recipient of the Russell A. Thom Award, which is presented to West Virginia's top basketball player.
Ostrowski had been staying at her sister's home in Bristol, where she received hospice care, Hundman said. Hundman described her sister as compassionate, humble person who didn't call attention to her basketball success.
"One of the things people keep saying is what a kind and gentle soul she was," Hundman said. "That is so true.
Hundman said a memorial "celebration" has been scheduled for next Saturday at the Knights of Columbus in Parkersburg, W. Va.