This research examines the rate of breastfeeding among mothers of very low birth weight infants (VLBW, < 1500 grams), and the correlates of breast milk pumping and transition to nursing at the breast. Eighty-two mothers and their 69 singleton and 21 twin VLBW infants admitted to the Neonatal Intensive Care Unit (January 1-June 30, 1995) of an urban tertiary care hospital. Maternal demographic, infant birth, and neonatal data were compared according to breast or bottle feeding, and a telephone interview was administered retrospectively to mothers pumping breast milk at the time of the infant's discharge home. Of 39 mothers who chose to pump breast milk, 19 were still pumping at the time of the infant's discharge home. Only 8 made a successful transition to nursing at the breast. Mothers who continued pumping tended to be white, married, and older, and their infants had fewer neonatal complications. The rates of prolonged breast milk pumping and of nursing are very low. Specific interventions and better support might improve the success rates.