The 1984 ATP Championship, also known as the Cincinnati Open, was a men's tennis tournament played on outdoor hard courts at the Lindner Family Tennis Center in Mason, Ohio in the United States that was part of the 1984 Volvo Grand Prix. It was the 83rd edition of the tournament and was held from August 20 through August 26, 1984. Third-seeded Mats Wilander won the singles title.
See main article: 1984 ATP Championship – Singles. 
Mats Wilander defeated Anders Järryd 7–6, 6–3
See main article: 1984 ATP Championship – Doubles. Francisco González / 
Matt Mitchell defeated Sandy Mayer / 
Balázs Taróczy 4–6, 6–3, 7–6