Male and female mice were treated with methamphetamine (10.0 mg/kg/injection for four injections) and sacrificed two weeks later. It was observed that the methamphetamine treatment caused depletions in striatal dopamine which were significantly greater in males (74%) than in females (56%). These results indicate that estrogen may have a protective effect against methamphetamine-induced dopamine depletions and may relate to the fact that males are more likely to incur Parkinson's disease than females.