Epichloë species and their anamorphic relatives in genus Neotyphodium are fungal symbionts of grasses ubiquitously existing in temperate regions all over the world. To date, 13 Epichloë species and 22 Neotyphodium species have been formally described, based on morphological characters and phylogenetic analyses. Leymus chinensis (Poaceae) is a dominant grass native to the Inner Mongolia steppe of China. Previously, it was reported to harbor endophytes, but little was known about these endophytes. To investigate their diversity and taxonomy, 96 fungal isolates were obtained from three field populations of L. chinensis. The isolates were classified into three morphotypes based on morphological characters and phylogenetic analyses of sequences of genes for β-tubulin (tubB), translation elongation factor 1-α (tefA), and actin (actG). The dominant morphotype, morphotype I, was identified as a choke disease endophyte, Epichloë bromicola. This broadened the host range and phylogenetic definition of E. bromicola.