Mastichochoria (Μαστιχοχώρια "the mastic villages" in Greek) is a former municipality on the island of Chios, North Aegean, Greece. Since the 2011 local government reform it is part of the municipality Chios, of which it is a municipal unit. It is located in the southwestern and extreme southern part of the island. It is the largest municipal unit in land area on Chios at 211.687 km². Its population was 4,744 at the 2001 census. The seat of the municipality was Pyrgi (pop. 1,044). The next largest villages are Kalamotí (718), Armólia (611), Mestá (501), and Lithío (455). The small coastal village of Emporio (47) boasts an archaeological site.
This area is well known for the production of mastic, from which it derives its name. Mastic is the hardened resin of the mastic shrub and is only harvested on Chios, being a major part of the local economy. In the village of Pyrgi, there is even a small Museum of Mastic.
In the Chios Massacre of 1822, during the Ottoman rule of Chios, the people of Mastichochoria were spared so that they could continue serve the Sultan by providing him and his harem with mastic.
In 2012 the Mastichochoria and its trees were threatened by a wildfire that broke out in the southern part of the island.