Cemais Is Nyfer was a commote in the Dyfed cantref of Cemais, Wales. It consisted of the territory between the rivers Nyfer and Teifi, and comprised the parishes of Eglwyswrw, Monington, St. Dogmaels, Llanfair-Nant-Gwyn, Llantood, Moylgrove and Bayvil, and parts of Nevern and Meline. Its area was about 100 km². Its civil and ecclesiastical headquarters were at Nevern.