Thirteen experienced male weightlifters taking high-protein diets and regular exercise took part in a double-blind crossover trial of methandienone 10 or 25 mg/day to seeif the drug improved athletic performance. Their improvemments were significantly greater on methandienone than on placebo; their body weights rose (though this seemed to be associated with water retention); and systolic blood pressure rose significantly. Methandienone caused many side effects, and three men had to withdraw because of them. All side effects disappeared after the drug was stopped. Anabolic steroids are effective only when given combination with exercise and high-protein diet. We deprecate their use in athletics but can suggest no way of stopping it.