The effect of Vitamins C, B-1 and B-6 on the superoxide dismutase (SOD) and the catalase (CAT) activities, membrane bound total sialic acid (TSA) and lipid peroxidation (LPO) levels in Fusarium equiseti and Fusarium acuminatum were investigated in different concentrations of each vitamin and the results were compared with control. SOD activities in both of the Fusarium strains decreased significantly with the increases in Vitamins C, B-1 and B-6 concentrations and all of these activities were lower than control. Although CAT activities for all vitamin concentrations used were lower than control in the case of F equiseti, these activities did not change significantly in F acuminatum and also for Vitamin B-6 supplemented conditions in F equiseti. The maximum SOD and CAT activities in all conditions were determined on the 12th day. TSA levels of E equiseti and F acuminatum grown in Vitamins C, B-1 and B-6 containing mediums were higher compared with controls especially after 12 days of incubation period. LPO level variations in both strains grown in Vitamins C and B-1 supplemented conditions were significantly higher than control although similar values were determined in the case of Vitamin B-6, Intracellular iron levels of F equiseti and F acuminatum increased significantly with respect to increases in Vitamin C concentrations. (c) 2006 Elsevier Ltd. All rights reserved.