The amount of (1 3)-ß-D-glucan was measured in three species of fungi during different phases of growth and after heatkilling. The amounts were the same in living and dead spores, but not related to the growing time intervals or media studied. The amount of (1 3)-ß-D-glucan was significantly higher in Stachybotrus atra than in Penicillium aurantiogriseum and Aspergillus fumigatus. The results suggest that airborne (1 3)-ß-D-glucan may be a better indicator of risk than airborne viable or dead spores.