San Martino in Pensilis is a comune (municipality) in the Province of Campobasso in the Italian region Molise, located about 45 km northeast of Campobasso. As of 31 December 2004, it had a population of 4,836 and an area of 100.3 km². San Martino in Pensilis borders the following municipalities: Campomarino, Chieuti, Guglionesi, Larino, Portocannone, Rotello, Serracapriola, Ururi.