Three women, previously diagnosed as bipolar I manic-depressive, were withdrawn from lithium carbonate prophylaxis immediately prior to their pregnancies. The patients had been euthymic while on lithium carbonate for at least 31/2 years prior to their pregnancies. Two of the three patients developed a manic syndrome within 2 weeks postpartum. The use of lithium carbonate during pregnancy, and particularly in the postpartum period, requires reassessment. We advocate an ongoing clinical relationship and the reinstitution of lithium in the third trimester in most cases.