Field work conducted over the past fifteen years in the Sierra Juárez of Oaxaca, Mexico, has resulted in three new species of grammitid ferns and a new state distribution record. Two of the new species, Ceradenia sacksii and Lellingeria labiakii, are known only from the vicinity of Cerro Pelón and Humo Chico, in the Sierra Juárez. The third new species, Mycopteris martiniana, is also known from similar habitats in the states of Mexico and Veracruz. All three species are illustrated with line art and photographs and distinguished from their most similar relatives. The new record, Ceradenia margaritata, was previously known in Mexico from Chiapas. With these new additions, 37 species of grammitid ferns distributed in ten genera are now known from Mexico. Twenty eight of these species occur in Oaxaca, which remains the Mexican state with the overall highest diversity of ferns.