The 2003 Daytona 500, the 45th running of the event, was the first race of the 2003 NASCAR Winston Cup season, having been held on February 16 at Daytona International Speedway in Daytona Beach, Florida. 2000 NASCAR Busch Series champion Jeff Green won his second career Winston Cup pole.

Prior to the race, the drivers paid tribute by having decals on their cars in honor of the astronauts who were killed in the Space Shuttle Columbia disaster two weeks earlier, similar to the 1986 Daytona 500, in which they paid tribute to the fallen crew members of the Space Shuttle Challenger disaster.

The race ended after 109 laps when rain had begun pouring on the track. Michael Waltrip won the race for the second time in three years, giving him his third NASCAR Winston Cup win; all of his wins to that point had been in races held at Daytona. It was the first of Waltrip's two wins in 2003, both coming in restrictor plate races (he later won the EA Sports 500 at Talladega in October for his fourth and last Cup win). For the first time since 1966, the race was stopped due to rain; at 272.5 miles, this was the shortest Daytona 500 ever.

In the race, Ryan Newman had a wild accident in the tri-oval, where his No. 12 Dodge tumbled end-over-end. He was not injured in the crash. Following the incident, both Penske Racing and new manufacturer Dodge were investigated because of the quality of the car.