There are fewer studies on the degradation of polyaromatic hydrocarbons (PAHs) by fungi than those by bacteria. Three fungi (strains A, B, and C), which could grow on pyrene as the sole source of carbon, were isolated from soils at the side of a freeway, a gas station, and a lake in Japan. Strain A was tentatively classified as members of the Trichoderma/Hypocrea genus, and both strains B and C were classified as belonging to the Fusarium genus on the basis of their base sequence of 18S ribosomal DNA and morphological characteristics. After an incubation period of 7 and 14 days at 28°C in an inorganic Czapek-Dox medium with PAHs as the substrate, both strains A and B assimilated anthracene and fluoranthene, whereas strain C assimilated neither of them. The pyrene-degrading activity and the growth of strain A improved by adding 0.02% yeast extract, 0.1% sucrose, or 0.1% lactose. The pyrene-degrading activity was also found to be more effective at pH 4 rather than at pH 6.5.