OBJECTIVE: This review explores the theoretical background for and empirical evidence supporting gender-related differences in pharmacokinetics and pharmacodynamic properties of psychotropic medications. METHOD: The authors reviewed all English-language articles on this topic that involved original research using human subjects. RESULTS: Limited evidence suggests that young women seem to respond better to and require lower doses of antipsychotic agents and benzodiazepines than young men. The administration of exogenous hormones interacts with medications, changing plasma levels and possibly conferring greater risks for toxicity. Young women may have an enhanced response to nontricyclic antidepressants. CONCLUSIONS: Too little basic and clinical research has been conducted on sex differences in therapeutic effects and side effects of psychopharmacological treatments. Addressing these differences as well as similarities will lead to safer and more effective treatment for all patients.