A study was conducted among 56 women in order to discover factors which might motivate them to breast-feed their premature infants. At three months of age, 54% of the infants were breast-fed. At six the figure was 29% and at nine months 25%. Low birth weight, low gestational age and the severity of neonatal complications were associated with short duration of lactation. If the mother smoked, the mean lactation period was three months compared with 5.5 months in a non-smoking mother, even if the child was critically ill. The lactation period was longer among mothers with a higher education. If the mother expressed milk more than five times a day the lactation period was likely to be long. The most frequent reason for cessation of milk production was declining volume of milk. Women who deliver prematurely should start to express breast milk preferably within the first days after delivery. Information and encouragement enhance milk yield and prolong the breast-feeding period.