This paper reports on a qualitative and quantitative cross-sectional study of infant feeding practices made in three neonatal intensive care units. Findings from interviews with 44 mothers of diverse ethnic origin, social class, age and gestation at delivery are reported. All the mothers interviewed had at some time provided breast milk and rates of breast-feeding on these units were higher than the national average. Eight mothers reported changing their mind about feeding methods after their baby was admitted, including three changes from formula to breast-feeding. Mothers' perceptions with regard to milk expression and their expressing history gave indications of factors underlying decisions to provide breast milk and the quality of support to do so. While mothers considered overall support to have been good, notably 35% of mothers had themselves suggested that they express milk, nearly half did not start expressing for 2 or more days, 43% expressed fewer than four times a day and 48% of mothers had received conflicting advice. There were some difficulties with both the hospital facilities and with expressing milk at home. There is a need for more consistent advice and practical help to be given to mothers.