In Victoria, Australia, the legal position regarding young people's competence to make medical treatment decisions has not been clarified in legislation, and a number of often vague common law decisions must be relied on for guidance. This situation produces a degree of uncertainty about appropriate professional practice, while also potentially impeding young people's rights claims in health care settings. With this in mind, the present research explored general practitioners' competence and confidentiality decisions regarding a 17-year-old female who presented with symptoms of an eating disorder. Questionnaires were sent to a random sample of 500 Victorian general practitioners, of whom 190 responded. After reading a case vignette, general practitioners indicated whether they would find the hypothetical patient competent and if they would maintain her confidentiality. Seventy-three per cent of respondents found the patient competent and most would have maintained confidentiality, at least initially. However, subsequent analysis of the rationales supplied for these decisions revealed a wide diversity in general practitioners' understandings and implementations of extant legal authority. This research highlights the need for general practitioners to be exposed to up-to-date and clinically relevant explanations of contemporary legal positions.