We isolated endophytic fungal strains from twigs of Larix gmelinii var. olgensis. These strains were identified based on their morphological characteristics and phylogenetic analyses including internal transcribed spacers and large subunit rDNA. We confirmed the presence of a previously unrecorded fungal species in Korea, Aequabiliella effusa. This study presents the morphological characteristics and phylogenetic analysis of A. effusa.