A STUDY WAS MADE OF THE FLORA AND VEGETATION IN THE ARE COMPRISED BETWEEN 1500 AND 2800 METERS ABOVE SEA LEVEL IN THE SULTEPEC MOUNTAINS, WHICH ARE LOCATED AT ABOUT 150 KM SOUTHWEST OF MEXICO CITY. THE FLORISTIC LIST IS BASED ON 1452 ENTRIES COLLECTED BETWEEN JUNE 1984 AND MAY 1987. IT COMPRISES 107 FAMILIES, 327 GENERA AND 507 SPECIES. THE BEST REPRESENTED FAMILIES ARE ASTERACEAE (48 SPECIES), POLYPODIACEAE (S.L.) (36 SPECIES), FABACEAE (32 SPECIES) AND LAMIACEAE (23 SPECIES). THE FOLLOWING VEGETATION TYPES WERE RECOGNIZED AND BRIEFLY DESCRIBED: CLOUD FOREST, OAK FOREST, PINE-OAK FOREST, AND TROPICAL DECIDUOUS FOREST.SE REALIZO EL ESTUDIO DE LA FLORA Y VEGETACIÓN DEL ÁREA COMPRENDIDA ENTRE LOS 1500 Y 2800 M DE ALTITUD EN LA SIERRA DE SULTEPEC, QUE SE LOCALIZA A 150 KM APROXIMADAMENTE, AL SUROESTE DE LA CIUDAD DE MÉXICO. LA LISTA FLORÍSTICA ESTA BASADA EN LA DETERMINACIÓN DE 1452 REGISTROS, COLECTADOS ENTRE JUNIO DE 1984 Y MAYO DE 1987. COMPRENDE 107 FAMILIAS, 327 GÉNEROS Y 507 ESPECIES. LAS FAMILIAS MEJOR REPRESENTADAS SON: ASTERACEAE (48 ESPECIES), POLYPODIACEAE (S.L.) (36 ESPECIES), FABACEAE (32 ESPECIES) Y LAMIACEAE (23 ESPECIES). SE RECONOCIERON Y SE DESCRIBIERON BREVEMENTE LOS SIGUIENTES TIPOS DE VEGETACIÓN: BOSQUE MESOFILO DE MONTAÑA, BOSQUE DE QUERCUS, BOSQUE DE PINUS-QUERCUS Y BOSQUE TROPICAL CADUCIFOLIO.