The 78-lap race was won from pole position by Brazilian driver Ayrton Senna, driving a McLaren-Honda. It was Senna's fourth victory from the first four races of the season, and his fourth Monaco win. Englishman Nigel Mansell finished second in a Williams-Renault, with Frenchman Jean Alesi third in a Ferrari. Alain Pros with this Ferrar 642 finished 5th. 

At the start, Senna got away well followed by Modena, Patrese, Mansell, and Prost. In the usual first corner mayhem Berger ran into the back of Piquet, dropping the Austrian to the back of the pack and breaking Piquet's suspension, Berger would later crash out. Senna quickly built up a huge lead over Modena and Patrese. Most of Senna's chasers were eliminated on lap 42 when Modena's engine blew in the tunnel, spreading oil on the track which caused Patrese to crashSenna now had a huge lead over Prost and Mansell, but the Englishman passed Prost with a daring move going into the chicane, and eventually started flying despite having problems earlier in the race. Prost would later pit to repair a damaged wheel causing a slow puncture, but the stop was very long and he dropped down to fifth.
Senna won his fourth Monaco Grand Prix in five years by 18 seconds over Mansell, Alesi, Moreno, Prost, and Pirro. Curiously, as Senna was slowing down after finishing the race, the pit crew mistakenly ordered him to take another lap, believing that he had crossed for the final lap.

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