The genus Trichoderma consists of globally distributed fungi. Among them, T. harzianum, is one of the most commonly collected Trichoderma species, which had been known as an aggregate species. In the present study, using a Trichoderma selective medium, 20 isolates belonging to 5 Trichoderma species of the Harzianum clad were isolated from soil samples collected from diverse geographical regions of Khorramabad County, Iran. Comparing the cultural and phenotypic criteria combined with molecular tests of the tef1 gene sequences of isolated fungi, five species namely, T. afroharzianum, T. atrobrunneum, T. guizhouense, T. harzianum and T. pholiotae were identified and their descriptions and figures are presented in this paper. T. harzianum had the highest frequency among the 5 species. T. pholiotae is reported for the first time from Iran
