The Association of Tennis Professionals (ATP) Tour is the elite professional tennis circuit organised by the ATP. The 1999 ATP Tour calendar comprises the Grand Slam tournaments, supervised by the International Tennis Federation (ITF), the ATP Super 9, the ATP Championship Series, the ATP World Series, the ATP World Team Cup, the ATP Tour World Championships and the Grand Slam Cup. Also included in the 1999 calendar are the Davis Cup and the Hopman Cup, which do not distribute ranking points, and are both organised by the ITF.
Andre Agassi finished the year ranked world No. 1 for the first time in his career. He won five titles during the season, including two majors at the French Open (completing the career Grand Slam) and the US Open. He also won an ATP Super 9 title and finished runner-up at another major at the Wimbledon Championships.