| Type: | GP |
| Grand Prix: | Monaco |
| Date: | 19 April |
| Year: | 1931 |
| Official Name: | III Grand Prix de Monaco |
| Country: | Monaco |
| Location: | Circuit de Monaco Monte Carlo |
| Course: | Street circuit |
| Course Mi: | 1.976 |
| Course Km: | 3.180 |
| Weather: | Sunny |
| Distance Laps: | 100 |
| Distance Mi: | 197.6 |
| Distance Km: | 318.0 |
| Pole Driver: | René Dreyfus |
| Pole Team: | Maserati |
| Pole Country: | France |
| Fast Driver: | Louis Chiron |
| Fast Team: | Bugatti |
| Fast Time: | 2:07 |
| Fast Country: | Monaco |
| Fast Driver2: | Luigi Fagioli |
| Fast Team2: | Maserati |
| Fast Country2: | Italy |
| Fast Flag Suffix2: | 1861 |
| Fast Driver3: | Achille Varzi |
| Fast Team3: | Bugatti |
| Fast Country3: | Italy |
| Fast Flag Suffix3: | 1861 |
| First Driver: | Louis Chiron |
| First Team: | Bugatti |
| First Country: | Monaco |
| Second Driver: | Luigi Fagioli |
| Second Team: | Maserati |
| Second Country: | Italy |
| Second Flag Suffix: | 1861 |
| Third Driver: | Achille Varzi |
| Third Team: | Bugatti |
| Third Country: | Italy |
| Third Flag Suffix: | 1861 |
The 1931 Monaco Grand Prix was a Grand Prix motor race held at the Circuit de Monaco on 19 April 1931.
With 16 Bugattis in a field of 23 cars, the event was close to being a single-make race. Among the 16 were four factory-team Type 51s driven by the Monegasque Louis Chiron, the Italian Achille Varzi and the French Albert Divo and Guy Bouriat. The real challenge came from the Maserati 8C 2500's driven by René Dreyfus, the Italian Luigi Fagioli and Clemente Bondietti. Rudolf Caracciola with his huge Mercedes SSKL (Super Sport Short Light-Weight) was uncompetitive as his larger car performed poorly around the tight Monaco track.
The race was between the blue cars from Molsheim and the red ones from Modena. When the start flag dropped it was Rene Dreyfus in his red Maserati who led into St. Devote, only to be passed by 'Williams' on the hill to the Casino, but his lead was short-lived as the Brit was sidelined by a broken valve spring, and his race was over. Achille Varzi and Caracciola started closing on Dreyfus and Varzi managed to overtake the Frenchman on the 7th lap. Caracciola struggled with a slipping clutch that gave in on lap 53.
Starting slowly, Louis Chiron eventually displayed his talents; gaining back ground with a new lap record time. He caught up with all his opponents and left them behind. Chiron, a native of Monaco, finished the race some 5 minutes ahead of Luigi Fagioli.
Jean Bugatti could not control his joy and jumped over the parapet of the bleachers and fell into Louis Chiron's arms. For the Monegasque, this Monaco Grand Prix victory really confirmed his reputation.
Louis Chiron's victory at Monaco would be the last for a Monegasque for 93 years until Charles Leclerc won the 70th edition of the event. [1]
| Starting grid — 1931 Monaco Grand Prix | |||
|---|---|---|---|
| width=150px |  DreyfusMaserati | ||
 StuberBugatti | |||
 AckerlBugatti | |||
 Grover-WilliamsBugatti | |||
| Caracciola Mercedes-Benz | |||
| Divo Bugatti | |||
| Lehoux Bugatti | |||
| Boillot Peugeot | |||
 BiondettiMaserati | |||
| Varzi Bugatti | |||
 ChironBugatti | |||
| von Morgen Bugatti | |||
| Zehender Alfa Romeo | |||
| Fagioli Maserati | |||
| Penn-Hughes Bugatti | |||
| Étancelin Bugatti | |||
| Howe Bugatti | |||
| Burggaller Bugatti | |||
 ZanelliBugatti | |||
| Bouriat Bugatti | |||
 CzaykowskiBugatti | |||
| zu Leiningen Bugatti | |||
| Pedrazzini Maserati | |||
Note: grid slots were determined by drawing lots (Birkin and Ivanowski had provisionally been due to start on the first and seventh row, respectively).[2]
| Pos | No | Driver | Car | Laps | Time/Retired | Grid | ||
|---|---|---|---|---|---|---|---|---|
| 1 | 22 | Louis Chiron | Bugatti T51 | 100 | 3:39:09.2 | 11 | ||
| 2 | 52 | Luigi Fagioli | Maserati 26M | 100 | +3:55.4 | 14 | ||
| 3 | 26 | Achille Varzi | Bugatti T51 | 100 | +4:04.0 | 10 | ||
| 4 | 20 | Guy Bouriat | Bugatti T51 | 98 | +2 laps | 20 | ||
| 5 | 46 | Goffredo Zehender | Alfa Romeo 6C-1750 GS | 97 | +3 laps | 13 | ||
| 6 | 38 | André Boillot | Peugeot 174S | 96 | +4 laps | 8 | ||
| Ret | 50 | René Dreyfus | Maserati 26M | 91 | Magneto | 1 | ||
| 7 | 48 | Clemente Biondetti | Maserati 26M | 91 | +9 laps | 9 | ||
| 8 | 12 | Clifton Penn-Hughes | Bugatti T35 | 89 | +11 laps | 15 | ||
| 9 | 30 | Stanislas Czaykowski | Bugatti T35B | 85 | +15 laps | 21 | ||
| Ret | 24 | Albert Divo | Bugatti T51 | 66 | Engine | 6 | ||
| Ret | 10 | Earl Howe | Bugatti T51 | 62 | Oil pipe/engine | 17 | ||
| Ret | 56 | Hans Stuber | Bugatti T35C | 59 | Drive shaft | 2 | ||
| Ret | 16 | Bernhard Ackerl | Bugatti T37A | 55 | Transmission | 3 | ||
| Ret | 8 | Rudolf Caracciola | Mercedes-Benz SSKL | 53 | Clutch/engine | 5 | ||
| Ret | 18 | Juan Zanelli | Bugatti T35B | 47 | Piston | 19 | ||
| Ret | 4 | Hermann zu Leiningen | Bugatti T35C | 31 | Gearbox | 22 | ||
| Ret | 6 | Heinrich-Joachim von Morgen | Bugatti T35B | 28 | Transmission | 12 | ||
| Ret | 2 | Ernst-Günther Burggaller | Bugatti T35B | 26 | Engine | 18 | ||
| Ret | 32 | Marcel Lehoux | Bugatti T35B | 15 | Transmission | 7 | ||
| Ret | 54 | Carlo Pedrazzini | Maserati 26B | 13 | Ignition | 23 | ||
| Ret | 28 | Philippe Étancelin | Bugatti T35C | 6 | Piston | 16 | ||
| Ret | 34 | William Grover-Williams | Bugatti T35C | 5 | Valve | 4 | ||
| DNS | 14 | Henry Birkin | Maserati 26M | |||||
| DNS | 36 |  Boris Ivanowski | Mercedes-Benz SSK | |||||
| DNA | 40 | Luigi Arcangeli | Alfa Romeo 6C-1750 | |||||
| DNA | 42 | Baconin Borzacchini | Alfa Romeo 6C-1750 | |||||
| DNA | 44 | Tazio Nuvolari | Alfa Romeo 8C-2300 | |||||
| Sources:[3] | ||||||||