Morphological study of several ectotrophic mycorrhizae of fir (Abies religiosa) showed that they are dichotomic or corralloid, simple or ramified. Four symbiotic fungi were isolated from the mycorrhizae, and judging from the type of infection, they were active and of medium virulence. The macro- and micro-scopic descriptions of each fungal strain show different cultural characteristics as well as different stimulations to the development of the plant.