Gymnastics chief Steve Penny had faced mounting calls to quit following allegations by hundreds of women who say they have been sexually abused, many of them by former national team doctor Larry Nassar during training camps.
"My decision to step aside as CEO is solely to support the best interests of USA Gymnastics at this time," Penny said in a statement, adding that he had been distraught to learn of the abuse claims.
More than 350 gymnasts were reportedly abused according to an investigation by the Indianapolis Star, from the city where USA Gymnastics is based, which found the national governing body did not ban coaches for several years even though after they had been convicted of sex crimes against children and sometimes failed to alert police of accusations.
Penny stepped down during a USA Gymnastics board of directors conference call. The panel accepted his resignation and named board chair Paul Parilla to guide the organization during the search for Penny's replacement.
The United States Olympic Committee, which had reportedly demanded Penny's resignation, welcomed his decision.
"Today's announcement will hopefully allow USA Gymnastics to shift its attention to the future with a secure environment for its athletes and continued success in competition," said US Olympic Committee chairman Larry Probst.