The anabolic agent stanozolol has been used to increase weight and activity in the elderly, but its long-term effect are largely unknown. A double-blind trial of stanozolol against placebo was continued for 12 months. Measuremtnes of weight, fat, fat-free mass, behaviour and activity were made at regular intervals, plus detailed biochemical and haematological profiles. There were no differences between the two groups in respect of weight, fat, fat-free mass and activity levels. There were significant increases in haemoglobin at six and 12 months and packed cell volume at 12 months in the active group. No androgenic side-effect were encountered.