The benefits of breast-feeding on newborn and infant health and for the maternal-infant relationship are well established. It is a failing of health care providers that breast-feeding is too frequently interrupted because of unfounded concerns over the potential adverse effects of concurrent drug therapy in the nursing mother. An overwhelming minority of medications are contraindicated during lactation, while the vast majority are considered either safe to use or the risk versus benefit considerations clearly favor use with continuation of breast-feeding. For those drugs that may pose a potential concern to the newborn, there are practical suggestions and precautions that can be taken to minimize risk. These include such interventions as selection of alternative effective drug regimens with safer profiles in breast-feeding, timing of drug dosing to minimize accumulation in the breast milk, surveillance for newborn or infant symptomatology that may be a sign of toxicity, or even the determination of drug levels in the infant's circulation. With a commitment to the advantages of breast-feeding and the information contained both herein and elsewhere regarding the interaction of medical therapy, pharmacology, and lactation, it is hoped that the health care provider will be empowered both to encourage and counsel more effectively the parturient who wishes to breast-feed but is concerned about ongoing drug therapy during lactation.