Long-term chronic treatment with stanozolol lacks significant effects on aggression and activity in young and adult male laboratory mice.

1. Repeated doses of the anabolic-androgenic steroid stanozolol were assessed for their effects on agonistic behavior, motor activity, and body weight in both young and adult male laboratory mice. 2. Stanozolol significantly increased weight gain in young, but not older subjects, especially at the highest doses. 3. There were, however, no significant differences in motor activity or in ethologically assessed social behavior (including aggression) in young or adult mice.