Samantha "Sam" Wopat, 19, had been in intensive care since she suffered an undisclosed medical emergency at her Stanford home on March 17, university officials said.
Wopat, a former junior Olympian and member of the 2010 U.S. Women's Junior National Team, joined the Stanford women's volleyball team in 2010 along with her twin sister, Carly.
Athletics director Bob Bowlsby said in a statement that university administrators, coaches and students are mourning Wopat's death.
"She was an integral member of the Stanford Athletics family and a tremendous student and athlete," Bowlsby said.
"Stanford University and the Women's Volleyball program have lost a wonderful young woman," he said.
Plans for memorial services have not yet been announced.