The growth inhibitory properties of derivatives of chalcone (1,3-diphenyl-2-propen-1-one) were studied against oral Candida species, including C. albicans. C. tropicalis and C. glabrata. The antifungal activities of 2-hydroxychalcone and 2,5-dihydroxychalcone were so high that they inhibited the growth of most strins at the concentration of 200 μg ml-1, whereas chalcone was less active (to a limited number of strains) or inactive. 2-Hydroxychalcone was active only against C. glabrata. The other chalcones without a 2-hydroxyl group showed no significant antifungal activity. The minimum inhibitory concentration of 2-hydroxychalcone was 75 μ ml-1 to all strains of three Candida species sensitive to it. The antifungal property was based on a fungicidal action. The structure-activity relationship indicates that the presence of a hydroxyl group at the 2-position potentially improves the antifungal property.