The 2008 Indianapolis motorcycle Grand Prix was the fourteenth round of the 2008 MotoGP Championship. It took place on the weekend of September 12–14, 2008 at the Indianapolis Motor Speedway – the first time the circuit has hosted a major motorcycle racing event since its first year of operation in 1909. As there was a United States Grand Prix at Mazda Raceway Laguna Seca earlier in 2008, this marks the championship's second visit to the United States in 2008, the first time this has ever happened. Unlike the Laguna Seca round, the meeting features the supporting 125cc and 250cc classes, marking their first visit to North America since 1994.

The 2008 Grand Prix motorcycle racing season was the 60th F.I.M. Road Racing World Championship season. The season consisted out of 18 races for the MotoGP class and 17 for the 125cc and 250cc classes, beginning with the Qatar motorcycle Grand Prix on 9 March 2008 and ending with the Valencian Community motorcycle Grand Prix on 26 October.