The activity of superoxide dismutase (SOD) and glutathione peroxidase (GSHPx), as well as the concentration of thiobarbituric acid reactive substances (TBARS) in tissues of transplantable melanoma in the golden hamster were measured and compared. Ten inbred male hamsters were used for the experiment. They were divided into two groups and were given Bomirski melanoma cells subcutaneously. The first group was given melanotic (Ma) melanoma cells. The second group was given amelanotic (Ab) melanoma cells. Thirty days after the transplantation the hamsters were dissected and the tumor tissues were taken and homogenized. A statistically significantly higher activity of the measured antioxidant enzymes was found in homogenates of Ma tumor than in homogenates of the Ab tumor. Activity of SOD is 8% higher in melanotic melanoma, 24% higher in CAT, and 45% higher in GSHPx. Statistically significant differences between TBARS concentrations were not confirmed. The higher activity of antioxidant enzymes in the melanotic tumor is a result of increased generation of oxygen-derived free radicals. It is presumed that it is strictly connected with intensified production of quinone and semiquinone radicals in the process of melanogenesis.