It was race 3 of 11 in both the 1969 World Championship of Drivers and the 1969 International Cup for Formula One Manufacturers.
The 80-lap race was won by Graham Hill, driving a works Lotus-Ford, after he started from fourth position.
It was Hill's 14th and final World Championship race victory, and his fifth Monaco win, a record that would stand for 24 years.
It was also the first win for a driver wearing a full face helmet in Formula One.
This was also the final Formula One race for Cooper as a constructor and Maserati as an engine supplier, Vic Elford finishing seventh and last in a car entered by Colin Crabbe.