"Because of both President and Mrs. Reagan, in particular Mrs. Reagan, we started a national conversation, when before nobody would talk about it. Nobody wanted to do anything about it," Clinton said on MSNBC on Friday, when she was in California to attend the former first lady's funeral.
"And, you know," she added, "that, too, is something that I really appreciate with her very effective low-key advocacy, but it penetrated the public conscience and people began to say, hey, we have to do something about this too."
The remark raised a storm of criticism from some of those who had been on the front lines of the fight against AIDS.
They accuse Ronald Reagan of ignoring growing concerns about the epidemic first diagnosed during his presidency in the 1980s.
Hours later, Hillary Clinton issued a correction on Twitter.
"While the Reagans were strong advocates for stem cell research and finding a cure for Alzheimer's disease, I misspoke about their record on HIV and AIDS," she wrote. "For that, I'm sorry."
Critics earlier took to social media.
"While I respect her advocacy on issues like stem cell and Parkinson's research, Nancy Reagan was, sadly, no hero in the fight against HIV/AIDS," tweeted Chad Griffin, president of the Human Rights Campaign, which advocates LGBT rights.
Ronald Reagan first mentioned "AIDS" in public in September 1985 when asked at a news conference about the need to fund research into a virus first seen as affecting only gay men and once called "gay cancer" and "gay plague."
"People died while Reagan administration officials ignored pleas from government scientists and did not allocate adequate funding for AIDS research until the epidemic had already spread throughout the country," wrote the journalist Randy Shilts in his book "And the Band Played On," about the disease's rise. He died of AIDS-related complications in 1994.
"Already, some said that Ronald Reagan would be remembered in history books for one thing beyond all else: He was the man who had let AIDS rage through America, the leader of the government that when challenged to action had placed politics above the health of the American people."