The fatty acid composition of some thermotolerant strains of Dactylaria gallopava isolated from coal spoil tips has been compared with that of the type strain of D. gallopava, the original isolation of which was from diseased turkey poults. In addition, the fatty acids of the mesophilic fungi Dactylaria ampulliforme and Scolecobasidium spp. were analyzed. The scolecobasidia and D. gallopava had the same qualitative fatty acid pattern, though quantitatively there were differences, the scolecobasidia having more highly unsaturated lipids than D. gallopava. D. ampulliforme contained the triply unsaturated γ-linolenic acid and eicosatrienoic acid, and in this respect differed from the scolecobasidia and D. gallopava, which appeared unable to synthesize trienoic acids.