Water-distilled essential oil of Chaerophyllum byzantinum Boiss., collected from Bursa, Uludag, in Turkey, was analyzed by GC and GC/MS. Sixty-five components were identified representing 94.6% of the oil. Sabinene (30.0%), p-cymen-8-ol (16.0%) and terpinolene (11.5%) were characterized as main constituents. The oil was tested on five Candida species and two strains of Candida albicans and showed good to moderate activity. The activity of the oil against C. glabrata was twice as good as that of ketoconazole. Copyright (c) 2005 John Wiley & Sons, Ltd.