The 2004 Cincinnati Masters (also known as the Western & Southern Financial Group Masters and Western & Southern Financial Group Women's Open for sponsorship reasons) was a tennis tournament played on outdoor hard courts. It was the 103rd edition of the Cincinnati Masters, and was part of the ATP Masters Series of the 2004 ATP Tour, and of the Tier III Series of the 2004 WTA Tour. Both the men's and the women's events took place at the Lindner Family Tennis Center in Mason, near Cincinnati, Ohio, United States. It was the first Cincinnati event to feature both men and women's draws since 1989.

Finals

Men's singles

🇺🇸 Andre Agassi defeated 🇦🇺 Lleyton Hewitt, 6–3, 3–6, 6–2

Women's singles

🇺🇸 Lindsay Davenport defeated 🇷🇺 Vera Zvonareva 6–3, 6–2

Men's doubles

Mark Knowles / 🇨🇦 Daniel Nestor defeated 🇸🇪 Jonas Björkman / 🇦🇺 Todd Woodbridge, 6–2, 3–6, 6–3

Women's doubles

🇺🇸 Jill Craybas / 🇩🇪 Marlene Weingärtner defeated Emmanuelle Gagliardi / 🇩🇪 Anna-Lena Grönefeld 7-5, 7-6(7–2)