Samassi is a comune (municipality) in the Province of Medio Campidano in the Italian region Sardinia, located about northwest of Cagliari and about south of Sanluri. As of 31 December 2004, it had a population of 5,332 and an area of .
Samassi borders the following municipalities: Furtei, Sanluri, Serramanna, Serrenti.