It was only a fortnight since Gilles Villeneuve had been killed at Zolder and the Formula 1 world was still reeling. Ferrari took only one car to the Principality. Otherwise the field was as normal with the addition of Emilio de Villota in an Onyx Racing March 821. There was some confusion because Avon had announced that it was pulling out of F1. March had given up with Pirelli and bought all the existing Avon stock but Ensign and Theodore were left without tyres. Theodore eventually did a deal with Goodyear but Ensign had to use leftover Avons. Prequalifying got rid of de Villota, Riccardo Paletti's Osella, Teo Fabi's Toleman, Chico Serra's Fittipaldi and Raul Boesel's March and in qualifying itself Roberto Guerrero (Ensign), Jochen Mass (March), Mauro Baldi's Arrows, Jean-Pierre Jarier's Osella, Jan Lammers's Theodore and Derek Warwick's Toleman all failed to make it.

At the other end of the grid René Arnoux took pole position for Renault with Riccardo Patrese second quickest in the Brabham-BMW. he was followed by Bruno Giacomelli's Alfa Romeo, Alain Prost's Renault, Pironi's Ferrari, Keke Rosberg's Williams and Andrea de Cesaris (Alfa Romeo). The top 10 was completed by Derek Daly's Williams, Michele Alboreto (Tyrrell) and John Watson (McLaren). There was trouble for Talbot Ligier with the new JS19 being declared illegal until changes had been made. The changes made the cars difficult to drive.

At the start Arnoux took the lead while everyone was fairly well behaved and so Giacomelli was second, Patrese third, Prost fourth and Pironi fifth. De Cesaris made a good start to get ahead of Alboreto and Rosberg. Prost quickly moved ahead of Patrese and then on lap four Giacomelli went out with an axle problem, which promoted Prost to second place. Nothing then changed until lap 15 when Arnoux spun and stalled. Prost was left in the lead but now Patrese began to close in. Further back Rosberg got ahead of Alboreto to claim fifth but otherwise the order was static. Pironi lost the nose of his Ferrari against a backmarker but it seemed to make little difference.

It was not until the closing stages of the race that things changed when rain began to fall. Rosberg was one of the first to go, hitting a barrier on lap 65. Then Daly did likewise at Tabac but managed to keep going, although the rear wing was gone and he was trailing oil. On lap 74 Prost went off heavily at the chicane and hit the barriers hard. He bruised his legs badly but was otherwise unhurt. This put Patrese into the lead but halfway around the 75th lap he spun at the Loews Hairpin. Pironi took the lead but he was going slower and slower as he set off on the final lap. The car was out of fuel. The lead would have passed to de Cesaris but he too was out of fuel. In theory Mansell was the man but Patrese had been pushed by marshals because his Brabham was in a dangerous position. It had rolled down the hill and bump-started. Riccardo drove through to win his first Grand Prix victory. He did not even know he had won.

In the end they gave Pironi second and de Cesaris third with Mansell and de Angelis fourth and fifth and the final point going to Daly.