Microsoft's chief executive, Steve Ballmer, met with Yahoo chairman Roy Bostock in New York this week, according to a report in The New York Times.
The newspaper cited an unnamed source who had been briefed on the meeting, but no details of the conversation have been released.
Yahoo's appointment of Carol Bartz as chief executive has heightened speculation that the companies may be able to agree on a takeover, with Microsoft possibly acquiring Yahoo's search engine business. (Msnbc.com is a Microsoft-NBC Universal joint venture.)
The news follows reports of an informal conversation between Bartz and Ballmer after she was selected by Yahoo's board.
Jerry Yang, who has stepped down as the head of Yahoo, let a deal with Microsoft fall through last year, angering many of the company's investors.
Yahoo didn't immediateley return a call for comment, and Microsoft declined to comment.