San Fruttuoso is a district of Monza, in Italy, which is bordered to the east by the districts of St. Joseph and Triante, on the south by the municipality of Cinisello Balsamo and west by the municipality of Muggiò.

There are 33,863 people residing in the district equal to 27.88% of the total population.

With these numbers the District 4 is the most populous of all the districts as Monza and by extension is not dissimilar from the others, has a population density second only to the central area of the city.

The presence of foreigners settled in the city is growing faster and for this district the number of resident foreigners is 1,818 which represents 5.35% of the population of the district.

Among the foreign nationalities most represented this constituency are the Ecuadorian, Romanian and Bulgarian.