The complex of the churches of Saint Constantine and Saint Mamas is located at Missochori, close to the capital of the island of Nissyros, Greece. The first church preserves wall-paintings dated to the end of the twelfth century, shared donation of two monasteries/churches. The paintings are partly repainted, probably in 1318/1319. Both the murals and the two inscriptions of the church provide new evidence concerning mediaeval Nissyros.