Because prophylactic lithium treatment is often given to manic depressive women of fertile age, the answers to five questions are pressing: (1) Does lithium administration during pregnancy expose the unborn child to risk of malformations? (2) Does such exposure lead to later developmental anomalies? (3) Do changes in the pharmacokinetics of lithium during pregnancy and delivery require special precautions? (4) Does lithium treatment during pregnancy exert other effects? (5) Is it advisable that women in lithium treatment breastfeed their infants? The author discusses these questions in the light of present-day knowledge and proposes guidelines for lithium treatment during pregnancy, delivery, and lactation.