This exploratory study compared the effect of two methods of breast feeding on breast engorgement, mastitis, infantile colic and duration of breast feeding. An opportunity sample of subjects was assigned either to the experimental group (prolonged emptying of one breast at each feed) (n = 150) or to the control group (both breasts equally drained at each feed) in= 152) and both groups were followed prospectively to 6 months after delivery. The experimental group had a lower incidence of breast engorgement in the first week (61.4% versus 74.3%; p < 0.02) and colic over the first 6 months (12% versus 23.4%; p < 0.02). There was no significant difference between the two groups in the incidence of mastitis over 6 months and the length of breast feeding (16.510.3 weeks versus 17.510 weeks experimental versus control group). The majority of mothers in the experimental group (63%) felt it necessary to offer the second breast at the end of a feed to satisfy their infant's hunger. The “perceived insufficient milk supply syndrome” was the main reason given for cessation of breast feeding in both groups. This study provides data to advise nursing mothers about these two methods of breast feeding.Breast engorgement, breast feeding methods, foremilk, hindmilk, infantile colic, mastitis