The effect of various dietary antifungal compounds on the performance of broiler chickens reared under field conditions was investigated. Dietary gentian violet (8 or 16 μg./g.) propionic acid (300 or 500 μg./g.) or a product containing certain enzymes and antioxidants had no beneficial or adverse effect on body weight, feed consumption or feed conversion efficiency of the chickens. At no time during the 6 week study was there evidence of obvious mold growth or mycotoxin formation in any of the rations.