Mazara del Vallo is a town and comune in the province of Trapani, southwestern Sicily, Italy. It lies mainly on the left bank at the mouth of the Mazaro river.

The province of Trapani is a province in the autonomous island region of Sicily, Italy. Following the suppression of the Sicilian provinces, it was replaced in 2015 by the free municipal consortium of Trapani. Its capital is the city of Trapani. It has an area of 2,469.62 square kilometres (953.53 sq mi) and a total population of 433,826 (2017). There are 25 comuni in the province.