This study was conducted to evaluate the effects of combined deficiencies of Se and vitamin E on catalase activity in order to investigate the possible interactions between Se, alpha-tocopherol, and catalase in lambs with white muscle disease (WMD). Ten healthy and fifteen WMD affected lambs of the Akkaraman breed were used. Serum a-tocopherol and Se levels, and catalase activity were analysed. The catalase activity as well as a-tocopherol and Se levels in lambs with WMD before the treatment (day 0), were found to be lower than those of the control group (P<0.001). Therefore, the catalase activity should be taken into consideration in lambs with WMD.