Trenno is a district (" quartiere") of Milan, Italy, part of the Zone 8 administrative division of the city. It borders on green areas to the north and west (on the Boscoincittà city park) and to the south (on the Parco di Trenno); to the east, it is adjacent to the Gallaratese district. Before being annexed to Milan, in 1923, it was an autonomous comune.
The district is mostly residential, with low- and medium-income apartment blocks dominating its skyline, although the centre has maintained much of the flavour of a country town (as well as a cascina, "Cascina Campi"); it also has large green areas, the most important of which is the eponymous Parco di Trenno. The district is quite isolated from Milan, being connected to the centre by a single bus line and a few thoroughfare, some of which were still country roads until the late 1990s. The closest stop of the Milan Metro subway is in Bonola, about 1 km from Trenno.