The survival of fungi from soil samples has been investigated after exposure to temperatures of 60, 70, 80 and 90 degrees C in Sabouraud agar. The least resistant fungi surviving 60 degrees C for 60 min were the Aspergillus (A.) niger group, Chaetomium spp, Penicillium spp, and Scytalidium lignicola. None of these survived 70 degrees C for 10 min. The next group surviving 70 degrees C for 60 min included the A. glaucus group, Byssochlamys nivea, Dichotomomyces cejpii, Gelasinospora spp, Rhizoctonium spp, and Talaromyces flavus; they did not survive 80 degrees C for 10 min. At 80 degrees C for 60 min, survival was seen for Aspergillus fumigatus, Aspergillus nidulans, Eupenicillium baarnense and Ulocladium spp; they did not survive 10 min at 90 degrees C. Acremonium sclerotigenum, Aspergillus ochraceus, Botryotrichum piluliferum, Byssochlamys fulva, Gilmaniella humicola, Neosartorya fischeri, Nodulisporium sp. and Talaromyces avellaneus survived heat treatment at 90 degrees C for 10 min and longer time with the two last being the most resistant. The phenomen of activation of dormant spores by thermal shock was not apparent.