BACKGROUND Both chronic kidney disease and haemodialysis are oxidative stresses, possibly contributing to the increased rate of cardiovascular and malignant disease in maintenance haemodialysis patients. The body’s defence mechanisms against oxidative insult, including activity of the antioxidant enzymes superoxide dismutase (SOD) and glutathioine peroxidase (GPx), are known to be deranged in these patients. METHODS This randomised controlled double-blind study assessed the effects of a micronutrient cocktail containing physiological doses of antioxidant vitamins and trace minerals on antioxidant enzyme activity in maintenance haemodialysis. 36 patients were randomised to treatment with placebo or micronutrient. SOD and GPx activity was analysed at baseline and after six months of treatment. RESULTS SOD levels did not change in the treatment group but fell significantly in controls, while GPx activity remained unchanged in controls but rose significantly in treated patients. CONCLUSION These results suggest a beneficial effect of the cocktail on antioxidant enzyme activity. Large scale studies to assess clinical outcome measures are indicated.