The 1991 Heinz Southern 500, the 42nd running of the event, was a NASCAR Winston Cup Series race held on September 1, 1991 at Darlington Raceway in Darlington, South Carolina. Contested over 367 laps on the 1.366 mile (2.198 km) speedway, it was the 21st race of the 1991 NASCAR Winston Cup Series season. Harry Gant of Leo Jackson Motorsports won the race. Kyle Petty returned to the race since breaking his leg at Talladega in May.