Alain Prost recorded his second victory of the season in the San Marino Grand Prix at Imola, with only the Ferrari of Rene Arnoux on the same lap at the end. The only moment of concern for Prost came when a carbon-fibre brake grabbed unexpectedly causing him to elegantly perform a 360 degree spin but he resumed unflustered.
Defending champion Nelson Piquet had qualified his Brabham on pole but Prost was quicker off the line and led him into the first corner. For the second race running Keke Rosberg found himself stuck on the grid, creating near chaos as cars veered round the stricken Williams. But unlike at Zolder there was no remarkable fightback and he quit after two laps.
At the first corner Patrick Tambay, who had won in a Ferrari 12 months earlier, collided with Eddie Cheever's Alfa Romeo. Cheever continued to finish seventh but Tambay was left striding back to the pits.
Niki Lauda had also had problems on the grid as he could not find first gear on his McLaren, but by the 12th lap he was up to fourth only for his engine to blow.
Piquet was next to lose time with a seized clutch and he was easy pickings for Warwick, and both Piquet and team-mate Teo Fabi retired with blown turbos on the 48th lap.
In the final stages the ban on refuelling made itself felt. Warwick was forced to ease off which allowed Arnoux and then the Lotus of Elio de Angelis past. Andrea de Cesaris decided to go for broke and attacked de Angelis but the battle did for both cars. The Ligier of de Cesaris ran out of fuel on the penultimate lap while de Angelis suffered the same fate on the final lap, although he was still classified third. Prost suffered no such alarms as his lead enabled him to go easy with his gear changes and he finished with 12 litres of fuel still left in his tank.
This was also the only time in Ayrton Senna's career he failed to qualify. A dispute with Pirelli meant Toleman did not run both cars on the Friday and Senna suffered a fuel pressure problem on the Saturday and was unable to make the grid.