Two-time Olympic medalist
Maroney, 21, made the allegation early Wednesday morning in a Twitter post with the hashtag #MeToo, which women have been using recently to share stories of being sexually abused and harassed in the wake of multiple allegations against powerful Hollywood producer Harvey Weinstein.
"Everyone's words over the past few days have been so inspiring to me," Maroney wrote. "I know how hard it is to speak publicly about something so horrible, and so personal, because it's happened to me too.
"People should know that this is not just happening in Hollywood. This is happening everywhere. Whereever there is a position of power, there seems to be potential for abuse. I had a dream to go to the Olympics, and the things that I had to endure to get there, were unnecessary, and disgusting."
Maroney, who in 2012 won a team gold medal and a silver for vault, goes on to accuse Nassar of molesting her under guise of giving her what he said was "medically necessary treatment that he had been performing on patients for over 30 years."
"It seemed whenever and wherever this man could find the chance, I was 'treated,'" she wrote. "It happened in London before my team and I won the gold medal, and it happened before I won my Silver.
"For me, the scariest night of my life happened when I was 15 years old. I had flown all day and night with the team to get to Tokyo. He'd given me a sleeping pill for the flight, and the next thing I know, I was all alone with him in his hotel room getting a 'treatment.' I thought I was going to die that night."
Already in a Michigan jail awaiting sentencing after pleading guilty to possession of child pornography this summer, Nassar is awaiting trial after being charged in February with sexually abusing nine gymnasts. He also has been sued by more than 125 women and girls alleging abuse.
Nassar has denied the charges. His lawyers and USA Gymnastics didn't immediately return the Associated Press' requests for comment on Maroney's allegations.
"Is it possible to put an end to this type of abuse? Is it possible for survivors to speak out, without putting careers, and dreams in jeopardy? I hope so," wrote Maroney, who stopped competing in 2013 and formally retired years later.
"Our silence has given the wrong people power for too long, and it's time to take our power back.
"And remember, it's never too late to speak up."