The 1951 Spanish Grand Prix was a Formula One motor race held on 28 October 1951 at Pedralbes Circuit. It was the eighth and final race of the 1951 Formula One season.

This race was determined by tyre choice – Ferrari chose a 16-inch rear wheel, whilst Alfa Romeo settled for the 18 inch, which proved to be the better of the two options. Juan Manuel Fangio led Alberto Ascari by two points before the race. Ascari led the race from José Froilán González, but the Ferraris suffered numerous tread problems. Piero Taruffi threw a tyre tread on lap 6 and was followed on lap 7 by Luigi Villoresi, Ascari on lap 8 and Gonzalez on lap 14. The Ferraris were forced to stop frequently to change tyres and Fangio comfortably won the race and his first drivers' title, after Ascari finished 4th was not able to overhaul Fangio's total. After the race, Alfa Romeo announced that due to lack of finances, they would not be competing in the 1952 season.