Santo Tirso (Portuguese pronunciation: [ˈsɐ̃tu ˈtiɾsu]) is a city and municipality located in the north of Porto Metropolitan Area, Porto District, Portugal. In the region, the Ave Valley, there is a large center of textile industry. The population in 2011 was 71,530, in an area of 136.60 km².
Another important center in the municipality is Aves.
The highest point in the municipality is in the Alto de S. Jorge, in the parish of Refojos, with 527 meters of altitude. The municipality's current perimeter is 69 kilometres (43 miles).
Freguesias do concelho de Santo Tirso
Administratively, the municipality is divided into 14 civil parishes (freguesias):
Santo Tirso is home of the historic football club Futebol Clube Tirsense.