This paper describes mycorrhizal character of the Formosan azalea (Rhododendron formosanum Hemsl.), an indigenous ericoid plant in the Sanlinchi forest of Central Taiwan. The root-fungus associations were categorized into 6 morphological types with light microscopy. The root ultrastructure examined with scanning electron microscopy revealed that hyphal complex and hyphal coil structures were present in cortical cells. The isolated fungal strains had slow-growing septate hyphae. The results suggested that the root-fungus association of the Formosan azalea belong to ericoid mycorrhiza.