"Everybody does," the former New York City mayor and Donald Trump supporter said.
Giuliani was attacking Hillary Clinton in an interview with NBC's Chuck Todd on "Meet the Press" the morning after Trump said -- with no evidence -- at a rally: "I don't even think she's loyal to Bill, if you want to know the truth. And really folks, really, why should she be?"
Not mentioned by Trump: He's had three divorces and faced accusations of infidelity himself. So has the thrice-married Giuliani.
Todd asked Giuliani if he's the right person to criticize Clinton's marriage.
Giuliani cited his pre-mayoral career as a Justice Department prosecutor.
"I'm the right person to level this charge, because I've never made such a charge, and I've prosecuted people who've committed rape," he said.
But, Todd responded, "You have your own infidelity charge."
"Well, everybody does," Giuliani said. "And I'm a Roman Catholic, and I confess those things to my priest. But I've never ever attacked someone who's been the victim ... of sexual abuse. Not only that, I put people in jail who've been the victim of sexual abuse."
Then, Giuliani complained about Todd's line of questioning.
"And I think your bringing up my personal life really is kind of irrelevant to what Hillary Clinton did. She's running for president, I'm not," said Giuliani, himself a presidential candidate in 2008, when he sought the GOP nomination, unsuccessfully.