San Martino Sannita is a comune, or municipality, located in the Campania region of southern Italy. It is situated within the Province of Benevento, positioned approximately 9 kilometers (5.6 miles) southeast of the city of Benevento and about 60 kilometers (37 miles) northeast of Naples.
The municipality covers a total area of 6.3 square kilometers (2.4 square miles). As of December 31, 2004, the population of San Martino Sannita was recorded at 1,247 residents.