USA Gymnastics, which counted Nassar as part of its medical staff or as national team doctor through four Olympic cycles, announced the resignations from its board of directors in a tweet. Chairman Paul Parilla, Vice Chairman Jay Binder and Treasurer Bitsy Kelley have resigned, effective Sunday, the tweet said.
The board of directors will name an interim chairperson as it searches for a permanent replacement.
"We support their decisions to resign at this time. We believe this step will allow us to more effectively move forward in implementing change within our organization," USA Gymnastics President Kerry Perry said, according to another tweet.
"As the board identifies its next chair and fills the vacant board positions, we remain focused on working every day to ensure that our culture, policies and actions reflect our commitment to those we serve," she said.
Nassar meanwhile has been sitting in an Ingham County, Michigan, courtroom listening to statements from gymnasts
and other young women who he is accused of abusing. More than 140 girls and young women have addressed the disgraced doctor during his sentencing hearing.
Nassar, who also served as a physician for Michigan State University athletics, has pleaded guilty to seven counts of criminal sexual conduct and admitted to sexually assaulting and abusing young girls under the guise of providing medical treatment.
John Manly, an attorney who represents survivors, said they welcomed the resignations. Manly called on Congress to hold hearings and "investigate" the United States Olympic Committee, Michigan State University and USA Gymnastics "in connection with the Larry Nassar scandal."
"Many of the Board Members who remain were well aware of USAG's concealment of sexual abuse, its noncompliance with reporting statutes and harsh treatment of sexual abuse survivors," Manly said in a statement. "In order for the sport to survive, the entire Board and Officers of USAG needs to be reconstituted. If that does not happen the United States Olympic Committee should decertify the organization and charter a new organization run by people that will put the safety of children and athletes ahead of money and medals."
Jason Cody, a Michigan State spokesman, said "any authority that wishes to investigate MSU, we will cooperate fully."
"We want to say again that we are truly sorry for the abuse Nassar's victims suffered, the pain it caused and the pain it continues to cause," he said in a statement. "But as we have said previously, any suggestion that the university covered up Nassar's horrific conduct is simply false. Nassar preyed on his victims, changing their lives in terrible ways."
In an earlier statement, USOC spokesman Mark Jones said the organization has "proactively arranged for multiple independent reviews of our safe sport policies and practices since 2010."
"We are open to any further process or review that could lead to a safer environment for athletes who participate in Olympic and Paralympic sports," he said.