Dunaway is just the latest in a recent series of senior-level executives exiting the company. She could not be reached over the weekend for comment.
Among the initiatives Dunaway was spearheading at Yahoo was Project Goldmine. That research identified female Chief Household Officers as the most important user base for Yahoo and its advertisers as it refines its strategy for programming and returns to its roots as an Internet "starting point" rather than a content creator.
Dunaway joined Yahoo 4-1/2 years ago after a successful brand marketing career with Frito-Lay. At Yahoo, she held responsibility for marketing and consumer experience. Under her leadership, Yahoo built a direct marketing team from scratch and created such branding initiatives as the Big Idea chair and marketer testimonial campaign.
"The team in place is my most important accomplishment, and hopefully will be my most lasting legacy," Dunaway wrote in an email posted on Valleywag, followed later on Friday with an email from Yahoo president Sue Decker praising Dunaway, wishing her well and outlining who will cover what upon Dunaway's departure.
Decker said a new head of marketing will be determined within the next few weeks, and David Riemer, leader of the Audience "Go to Market" team will be the interim point person. The Brand team, meanwhile, will be led by Allen Olivo, who will also serve as acting leader for the Customer Experience division.
Last week, Yahoo reported strengthened revenues, but profits remained down 5% compared to last year.
Earlier this month, CEO Jerry Yang articulated for Yahoo staff a corporate strategy emphasizing more of a back-to-roots "starting point" strategy with a technology focus and emphasis on building a behavioral ad exchange.
Other recent high-level departures include senior sales executive Wenda Harris Millard, CTO Farzad Nazem, head of entertainment and media Lloyd Braun, and COO Dan Rosensweig. In June, Yang replaced Terry Semel as chief executive.