We present the case of a woman with bipolar I disorder with severe premenstrual mood instability, confusion, and psychosis resembling the clinical features of postpartum psychosis when estrogen levels are expected to be low, and hypomania when estrogen levels are expected to be elevated. While depressive symptoms across the menstrual cycle have been extensively documented in the literature, there is little information regarding manic and hypomanic symptoms. In addition, we describe the successful treatment of her menstrual-cycle related symptoms. Approaches to the management of menstrual psychosis have not been systematically studied, and clinical guidelines do not exist. Clinical experiences such as the one reported here, in which the clinical formulation of the patient was consistent with known neuroendocrine phenomena and in which the treatment approach was successful, are crucial to developing promising approaches that can be tested in controlled trials.