This study aimed to report on adverse infant and maternal clinical outcomes, and investigate the relationship between infant feeding practice and such adverse clinical outcomes in infants during the first 6 weeks postpartum. From an eligible sample of 450 mother-term infant pairs recruited from the Coombe Women and Infants University Hospital in Dublin, 27.1% of infants (n=122) were maternally reported to have had an illness during the first 6 weeks that necessitated the provision of prescribed medication +/- general practitioner/paediatrician attendance +/- hospitalisation. Of these, 90 infants had > or =1 episode of infection +/- viral +/- gastro-intestinal-related condition. After adjustment, 'any' breastfeeding to 6 weeks was protective against such adverse infant outcomes (adjusted odds ratio [aOR] 0.44, P = 0.022). Attendance to the GP/paediatrician for > 1 visit (aOR 3.44, P = 0.000) and multiparity (aOR 1.76, P = 0.041) were also positively associated with such adverse infant outcomes. To decrease infant morbidity rates in Ireland, government investment in breastfeeding promotion, support and research should be a continued public health priority.