The 92nd Indianapolis 500 was held at the Indianapolis Motor Speedway in Speedway, Indiana on Sunday May 25, 2008. It was the fifth round of the 2008 IndyCar Series in DIRECTV HD season. Scott Dixon of New Zealand won the race from the pole position. It marked the first Indy 500 victory for Chip Ganassi Racing since 2000. Dixon led 115 laps (of 200), taking the lead for the final time during a sequence of yellow-flag pit stops on lap 172. Dixon held off Vítor Meira and Marco Andretti over the final 24 laps to secure the win.

The 2008 Indy 500 took place just three months after the "Open-wheel Unification" took place. An organizational "Split" had lasted from 1996 to 2007, fracturing the sport, dividing participants, and imbittering fans. For the first time since 1978, the sport of Indy Car racing was unified under one sanctioning body. The 2008 field featured a full complement of IndyCar Series regulars, as well as several teams and drivers from the now-shuttered Champ Car World Series. Following the organizational merger, the 2008 running was expected to be one of the most competitive in many years. However, most of the former Champ Car teams struggled a bit to adapt to the new equipment. The transitioning Champ Car teams were provided a fleet of IRL chassis for the season, but many were used having been sold off by defunct teams. IRL/IndyCar Series-based teams swept the top ten finishing positions, with the best former Champ Car team finishing 11th.

It was the first Indy 500 where all 33 qualifiers utilized the Dallara IR-03/IR-05 chassis, which first saw competition in the 2003 season. Phil Giebler failed to qualify with the Panoz chassis (formerly known as the G-Force GF09), the final appearance at Indy for the brand. Panoz had already ceased supporting their chassis program in 2006, effectively ushering in a four-year "spec" era. In addition, all full-time entries began utilizing semi-automatic paddle shifters in 2008. Paddle shifters for part-time Indy 500-only entries were optional due to cost reasons. IndyCar Series practice began May 4. Time trials took place over the two weekends prior to the race (May 10–11 and May 17–18). The final practice was held Friday May 23.

The official entry list was released April 11. The initial list featured 39 cars and 32 drivers. Additional drivers were announced during practice and qualifying. Ryan Hunter-Reay, the 2007 IndyCar Series rookie of the year was eligible to compete for the Rookie of the Year award, under race rules. Even though he was an established IndyCar driver, he had not yet made a start at Indianapolis. Several other former Champ Car drivers were individually evaluated and some were only required to take a "refresher" level test in lieu of the traditional four-phase rookie test.

Failed to qualify

At 1:03 p.m., Mari Hulman George gave the command to start engines. All cars except Sarah Fisher pulled away, but Fisher quickly caught up to the field. Emerson Fittipaldi was booed during the parade laps due to his incident where he drank orange juice instead of milk after winning in 1993. He pulled the pace car off the track after the third pace lap, and a well-aligned field took the green flag. Polesitter Scott Dixon took the lead into turn one, and led the first two laps. His teammate Dan Wheldon took the lead on lap three. On the 8th lap, Bruno Junqueira lost a mirror, and the first of many caution periods slowed the field.

Nearly the entire field pitted on the first caution, with Buddy Rice staying out to lead. Sarah Fisher also stayed out, and moved to third. Moments later, she spun in the north chute while warming her tires, and lost 3 laps. When the green resumed, Dan Wheldon quickly regained the lead. He held it until lap 36, when Dixon passed him. At the same time, rookie Graham Rahal drifted high and hit the wall exiting turn four.

Marty Roth and Jaime Camara each brought out the yellow in the first half, suffering single-car crashes. Wheldon and Dixon continued to trade the lead.