The presentation and course of bipolar disorder differs between women and men. The onset of bipolar disorder tends to occur later in women than men, and women more often have a seasonal pattern of the mood disturbance. Women experience depressive episodes, mixed mania, and rapid cycling more often than men. Bipolar II disorder, which is predominated by depressive episodes, also appears to be more common in women than men. Comorbidity of medical and psychiatric disorders is more common in women than men and adversely affects recovery from bipolar disorder more often in women. Comorbidity, particularly thyroid disease, migraine, obesity, and anxiety disorders occur more frequently in women than men, whereas substance use disorders are more common in men. Although the course and clinical features of bipolar disorder differ between women and men, there is no evidence that gender affects treatment response to mood stabilizers. However, women may be more susceptible to delayed diagnosis and treatment. Treatment of women during pregnancy and lactation is challenging because available mood stabilizers pose potential risks to the developing fetus and infant. Pregnancy neither protects nor exacerbates bipolar disorder, and many women require continuation of medication during the pregnancy. The postpartum period is a time of high risk for onset and recurrence of bipolar disorder in women, and prophylaxis with mood stabilizers might be needed. Individualized risk/benefit assessments of pregnant and postpartum women with bipolar disorder are required to promote the health of the woman and avoid or limit exposure of the fetus or infant to potential adverse effects of medication.