Trichoderma taxi sp. nov. was isolated as an endophytic fungus of Taxus mairei growing at the Guanshan Nature Reserve of Jiangxi province, China, and characterized by a combination of phenotypic characteristics and gene analyses of ITS1 and 2, tef1 and rpb2 gene sequences. Distinctive morphological characters of Trichoderma taxi are its white small subglobose conidia and pachybasium-like conidiophores aggregated into compact pustules. Phylogenetically, Trichoderma taxi forms an independent branch in vicinity to the Lutea (Hypocrea lutea, Hypocrea melanomagna) and Pachybasioides (Hypocrea pachybasioides, Hypocrea minutispora, Hypocrea pilulifera, Hypocrea parapilulifera, Hypocrea lacuwombatensis and Hypocrea stellata) clades.