Cassacco is a comune in the Regional decentralization entity of Udine in the Italian region of Friuli-Venezia Giulia, located about 80 kilometres northwest of Trieste and about 12 kilometres northwest of Udine. As of 31 December 2004, it had a population of 2,880 and an area of 11.6 square kilometres. The municipality of Cassacco contains the frazioni Conoglano, Martinazzo, Raspano, and Montegnacco.