INTRODUCTION AND AIMS: The aim of this study was to determine the extent to which parent and adolescent characteristics predict parental supply of full serves of alcohol (i.e. not simply sips) to their adolescent aged 14-16 years. DESIGN AND METHODS: In 2009, a cross-sectional sample of 388 parents from Victoria, Australia was surveyed. RESULTS: Of the 70% of parents who believed that their adolescent currently drinks, 37% reported supplying their underage adolescent with more than a sip of alcohol in the last 3 months. Alcohol supply was significantly associated with parents' perceptions that their adolescent drinks, odds ratio 1.87 (95% confidence interval 1.38-2.53) and higher levels of parental monitoring, odds ratio 1.44 (95% confidence interval 1.10-1.94) but not significantly associated with parent/adolescent sociodemographic characteristics or parents' drinking patterns. DISCUSSION AND CONCLUSIONS: Consistent with reports from Australian students, parents are a major source of supply of alcohol to underage adolescents. While there are legislative and policy guidelines regarding the use of alcohol by underage adolescents, parents need support to implement and reinforce alcohol-specific rules for their children.