The 1999 American Le Mans Series was the inaugural season of the IMSA American Le Mans Series, and is now recognised as the 29th season of the IMSA GT Championship. It was a series for Le Mans Prototypes (LMP) and Grand Touring (GT) race cars divided into three classes: LMP, GTS, and GT. It began March 20, 1999, and ended November 7, 1999, after eight races.
The American Le Mans Series officially replaced the dwindling IMSA GT Championship after the 1998 season. The Automobile Club de l'Ouest (ACO), which organized the 24 Hours of Le Mans, allowed IMSA's owner Don Panoz to create a series closely modeled after the formula used at Le Mans. The first official ACO-backed event had been held at the 1998 Petit Le Mans, which was part of the IMSA GT season but allowed ACO-spec cars to compete. The success of the event allowed Panoz to form the American Le Mans Series, which continued until its merger with Grand-Am in 2013.