town and episcopal see, Trapani provincia, western Sicily, Italy, at the mouth of the Mazaro River south of Trapani city. Of Phoenician origin, the town was later colonized by Greeks from nearby Selinus (modern Selinunte). It fell to the Carthaginians in 409 BC and subsequently to the Romans, Saracens, and Normans. The first Norman parliament in Sicily met there in 1097. Notable buildings are the cathedral (1075; rebuilt 1694), the Norman church of San Nicolò, and the palace of the Knights of Malta, housing a civic museum of art and archaeology.

One of the most important fishing (tunny, coral) ports in Italy, Mazara del Vallo also has a busy export trade in Marsala wine and local agricultural produce. Pop. (2001 prelim.) 48,156.