Tissi is a comune located in the Metropolitan City of Sassari within the Italian region of Sardinia. It is situated approximately 6 kilometres (4 mi) south of Sassari and about 170 kilometres (110 mi) northwest of Cagliari.
As of December 31, 2004, the municipality covered an area of 10.3 square kilometres (4.0 mi2) with a population of 2,017 residents.