Objective: to explore fathers' experiences of the breast feeding of their very-low-birthweight preterm babies from birth to 12 months of age. Design: a qualitative study using interpretive phenomenology. Data were collected via longitudinal in-depth individual interviews. Setting: publicly funded tertiary level hospital, Australia. Participants: a purposive sample of 17 Australian parents took part in the broader study. This paper reports on data from the seven participant fathers. Findings: this paper explores the discursive changes in fathers' accounts of their perspectives on and support of the breast feeding of their preterm baby. The fathers' accounts highlight their marked influence on breast feeding, their ambivalent experiences related to breast feeding and their struggle in negotiating a parenting role related to baby feeding. Key conclusions: this study highlights the role and influence that fathers of preterm babies have on breast feeding, and explores the tensions and paradoxes inherent in promoting the ideology of breast feeding while valuing the practice of bottle feeding. Implications for practice: this study highlights the need to encourage and involve fathers in breast-feeding education including the impact of bottle feeding on breast-feeding outcomes. The active and positive contribution that fathers make towards preterm breast feeding should be acknowledged and encouraged.