The 1985 Italian Grand Prix was a Formula One motor race held at Monza on 8 September 1985. It was the twelfth round of the 1985 FIA Formula One World Championship.

The race was won by Frenchman Alain Prost driving a McLaren. It was Prost's fifth and final victory of the 1985 season as he powered towards the first of his four Formula One world championships. Prost won by almost 52 seconds over the Brazilian duo Nelson Piquet and Ayrton Senna.

It was the debut race for the American owned Haas Lola team with their new car, the Lola THL1 running the Hart 415T turbocharged engine, driven by Australia's 1980 World Champion Alan Jones.

Missing from the grid was popular West German driver Stefan Bellof who was killed a week earlier in a World Sportscar Championship race at the Spa Circuit in Belgium. With his funeral set for the day after the Italian Grand Prix the Tyrrell team only ran the one car for Martin Brundle. Members of the Tyrrell team, including team boss Ken Tyrrell, attended Bellof's funeral the next day.

Also missing were the West German Zakspeed team because their driver Jonathan Palmer had broken his leg when he also crashed his Porsche 956 at the 1000 km of Spa the weekend before. With only a week until the Italian Grand Prix and no spare driver the team was forced to miss the race.

Senna's pole position is often cited as one of his greatest moments.