The 1955 Monaco Grand Prix was a Formula One motor race held at Monaco on 22 May 1955. It was race 2 of 7 in the 1955 World Championship of Drivers. The 100-lap race was won by Ferrari driver Maurice Trintignant after he started from ninth position. Eugenio Castellotti finished second for the Lancia team and Maserati drivers Jean Behra and Cesare Perdisa came in third.

Moss and Fangio run 1–2 until half distance, trailed by Ascari and Castellotti. At the halfway mark, Fangio retired with transmission trouble. In Lap 80 a seemingly sure win for Moss was ended when his Benz's engine blew. The new leader, Ascari, miscalculated the chicane coming out of the tunnel, and his Lancia crashed through the barriers into the harbour. Ascari had to swim to safety. Maurice Trintignant, in a Ferrari 625 thought to be uncompetitive, inherited the lead and scored his first Formula One victory.

This was the last Grand Prix appearance for Alberto Ascari; he was killed four days later testing a Ferrari sports car at Monza.

Maurice Bienvenu Jean Paul Trintignant, French, competed in the Formula One World Championship for fourteen years, between 1950 and 1964, one of the longest careers in the early years of Formula One. During this time he also competed in sports car racing, including winning the 1954 24 Hours of Le Mans race. He won again in Monaco in 1958 with Cooper-Climax. Following his retirement from the track Trintignant concentrated on the wine trade.

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