Samassi is a comune (municipality) in the Province of South Sardinia in the Italian region Sardinia, located about 35 kilometres (22 mi) northwest of Cagliari and about 9 kilometres (6 mi) south of Sanluri. As of 31 December 2004, it had a population of 5,332 and an area of 42.2 square kilometres (16.3 sq mi).