A 20-year-old woman with a history of pituitary resection complicated by diabetes insipidus was able to fully breastfeed for three months despite apparent hyposecretion of pituitary hormones. This case report adds to the growing body of evidence that control of milk production shifts from endocrine to autocrine control shortly after delivery. Autocrine control allows efficient regulation of milk supply to match the needs of the infant. A recently discovered factor in human milk that inhibits lactose and casein synthesis in vitro is believed to be responsible for local, short term control of milk production. This study suggests that practices which result in infrequent or incomplete removal of milk from the breast lead to decreased milk production and should be abandoned.