Objective. To compare the uptake of peer review among interns in mandatory and voluntary peer-review programs. Population. All first and second year graduates (n=105) in two Australian hospitals. Main outcome measures. Completion of peer review, and reported responses by doctors to peer review. Results. Eight of sixty interns undertaking the mandated program completed all steps. In the voluntary program, none of 45 interns did so. Resistance to peer review occurred at all stages of the trial, from the initial briefing sessions to the provision of peer-review reports. Discussion. Hospital internship is a critical period for the development of professional identity among doctors. We hypothesise that resistance to peer review among novice doctors reflects a complex tension between the processes underpinning the development of a group professional identity in hospital, and a managerial drive for personal reflection and accountability. Peer review may be found threatening by interns because it appears to run counter to collegiality or 'team culture'. In this study, resistance to peer review represented a low-cost strategy in which the interns' will could be asserted against management. Conclusion. To enhance uptake, peer review should be structured as key to clinical development, and modelled as a professional behaviour by higher-status colleagues. What is known about this topic? In non-clinical settings, peer review can lead to improvements in performance. Studies in the US and Canada have demonstrated that junior doctors in hospital have low rates of uptake of peer review. What does this paper add? In Australia, junior doctors had low rates of engagement with both mandatory and voluntary peer review. Peer review may be resisted because it threatens to undermine the collegiate atmosphere among hospital peers. What are the implications for practice? Peer review should be modelled as professional behaviour by higher-status colleagues, especially registrars and consultants, and presented as central to improvement in clinical skills.