This study followed a prospective cohort of 306 breastfeeding mothers for the first three months postpartum and identified a cumulative incidence rate for lactation mastitis of 27.1% and a cumulative recurrence rate of 6.5%. Mastitis was given as the reason for cessation of breastfeeding by 18% of women who ceased to breastfeed. It was the third most commonly stated reason given for cessation of breastfeeding. Fifty-one percent of cases occurred within the first two weeks postpartum. Early onset mastitis and the severity of localised symptoms were associated with bilateral mastitis and protracted outcomes.