Oio is a region in Guinea-Bissau. Its capital is Farim. Other major cities and towns include Nhacra, Mansôa, Bissorã and Cumeré. The region borders Senegal to the north, the Guinea-Bissau regions of Bafatá, Bissau and Biombo to the east, the Rio Geba/Guinea-Bissau region of Quinara to the south and the Guinea-Bissau region of Cacheu to the west. The Rio de Canjambari flows through the north of the region.