Postpartum major depression occurs in approximately one of 10 childbearing women and is considerably underdiagnosed. If left untreated, the disorder can have serious adverse effects on the mother and her relationship with significant others, and on the child's emotional and psychologic development. A simple screening instrument can be used to increase the detection of postpartum major depression. Although few well-controlled studies have been done to support the use of any one modality, the mainstay of treatment has been antidepressant therapy, alone or in combination with psychotherapy. Plasma concentrations of antidepressant drugs are usually low in the breast-fed infant, and most studies demonstrate that certain antidepressants can be used during lactation without any important adverse effects on the infant.