The antifungal activity of flavone and flavanone was tested in three different concentrations, 0·5, 2 and 8 × 10−4 M, against 34 fungi. In general, flavone was the substance with the higher activity, and could at 2 × 10−4 M completely inhibit several fungi. No linear relationships between the concentration and the antifungal activity could be observed for some fungi. Chaetomium globosum was the only fungus which was totally inhibited by flavanone at 8 × 10−4 M. Several fungi did, however, show a higher inhibition rate at 2 × 10−4 M.