Case will remain a member of the company's board, he said in a press release issued Sunday night.
"Given that some shareholders continue to focus their disappointment with the company's post-merger performance on me personally, I have concluded that we should take steps now to avoid the possibility of that effort hindering our ability to pull together as a team and focus fully on our businesses," Case said.
Case, the architect of America Online's blockbuster merger with Time Warner, has not had a major day-to-day role in overseeing operations, but he has nonetheless come in for sharp criticism for the company?s woes.
That merger has involved a good deal of shuffling in the executive ranks. Former AOL Time Warner Chief Operating Officer Robert Pittman left the company earlier this year. CEO Richard Parsons replaced Gerald Levin in 2001.
But financial woes have been as big a problem for the company, many involving the AOL service. In December, the company cut the advertising and commerce outlook for its AOL division, although it said that the decline would be offset by growth in subscriptions and that overall revenue would be flat.
The company has also been dealing with an investigation by the Securities and Exchange Commission and the Justice Department for the way it accounted for certain advertising transactions engineered by AOL.
The multibillion-dollar merger came at the height of the Internet boom. But in the following years, the glow of AOL has dimmed significantly. The parent company is expected to take a major charge in the fourth quarter to write off some of the costs of the deal. As one of the few remaining AOL executives, Case has come in for much of the criticism.
Case said in a release that he would continue to co-chair the company's strategy committee, and would advocate "a forward-looking view."
"The bottom line is this: I love the company and will do whatever I can to make it successful. I believed in America Online when we built it; I believed in AOL Time Warner when we created it; and I continue to believe in the great potential of this company and its people," Case said. "While my role will change, my enthusiasm for what this company can accomplish won't diminish."
AOL's stock rose 44 cents to $15.32 in morning trading Monday.