The Province of Siena (Italian: Provincia di Siena) is a province in the Tuscany region of Italy. The capital of the province is the city of Siena.
The province has an area of 3,821 km² (1475 mile²) and a total population of 252,288 (2001). There are 36 comuni (singular: comune) in the province. At June 30, 2005, the main comuni by population are:
The province is divided into seven historical areas: