The 2009 Cincinnati Masters was a tennis tournament played on outdoor hard courts. It was the 108th edition of the Cincinnati Masters, and was part of the ATP Masters Series of the 2009 ATP World Tour, and of the Premier Series of the 2009 WTA Tour. Both the men's and the women's events were held at the Lindner Family Tennis Center in Mason, near Cincinnati, Ohio, United States, with the men playing from August 17 through August 23, 2009, and the women from August 10 through August 16, 2009. It was the third women's event and the fifth men's event on the 2009 US Open Series. Former world No. 1 Kim Clijsters made her return to the Sony Ericsson WTA Tour in Cincinnati.