The Republican nominee denied ever sexually assaulting women, but turned his fire on ex-President Bill Clinton in a bitter US presidential debate.
“There’s never been anybody in the history of politics that has been so abusive to women,” he said.
Hillary Clinton refused to address his comments about her husband.
Mr. Trump’s attack on the Clintons came after moderator Anderson Cooper asked him about a 2005 video released on Friday that revealed Mr. Trump bragging about groping women.
The 70-year-old billionaire dismissed the remarks as “just words” and “locker room talk”.
When pressed on whether he had engaged in sexual misconduct, he denied doing so and instead focused on Mr. Clinton’s previous indiscretions.
No criminal charges have been brought against Mr. Clinton in any allegations of sexual assault.
Mrs. Clinton said the explosive video, which has sparked an exodus of Republicans denying support to their presidential nominee, “represents exactly who he is”.
“With prior Republican nominees, I disagreed with them,” she added, “but I never questioned their fitness to serve.”
When the two took to the stage in St. Louis for their second of three debates, they did not shake hands, striking a bitter tone that would continue throughout.
Mr. Trump said if he won, he would appoint a special prosecutor to investigate Mrs. Clinton and she would be in prison over her private email arrangements.
“Everything he just said is absolutely false but I’m not surprised,” she responded. “It’s just awfully good that someone with the temperament of Donald Trump is not in charge of the law in our country.”
“Because you’d be in jail,” he interrupted.