OBJECTIVE: Although sex differences occur with some psychotropic drug treatments, they are not well defined for mood-stabilizing agents, including lithium. The authors’ goal was to investigate whether there are differences between the sexes in response to lithium. METHOD: Studies identified in a literature search were analyzed for reports of sex differences in clinical response to lithium in major affective syndromes. RESULTS: Data from 17 studies published in 1967–1998, involving 1,548 adults treated with lithium for a mean of 38.6 months (SD=30.5), yielded similar weighted response rates to lithium in 1,043 women (65.6% [N=684]) and 505 men (61.0% [N=308]). CONCLUSIONS: The results indicate little difference between the sexes in clinical response to lithium treatment of bipolar and related affective disorders.