Research into adolescent health issues is hampered by absolute requirements for parental consent. Society's recognition of adolescents' autonomy and decision-making capacity has been embodied in the legal recognition of the mature minor's right to make decisions on matters affecting his or her life. Psychological research indicates that young people from 14 years have decision-making capacity. US and UK research ethics guidelines acknowledge the mature-minor principle, but Australian guidelines are out of step with international practice. An absolute requirement for parental consent in Australian research ethics guidelines is potentially unethical if it denies mature adolescents' autonomy and is a barrier to participation, study validity and improved health outcomes through research findings. There are grounds for considering a mature-minor clause in the National Health and Medical Research Council research ethics guidelines, particularly in the context of youth participation in minimal-risk research.