Recent interest has focused on the association between cannabis use and risk of psychosis. In the largest unselected, population-based study on this topic to date, we examined cannabis use and prodromal symptoms of psychosis at age 15-16 years among 6330 adolescents. Those who had tried cannabis (n=352; 5.6% of the total sample) were more likely to present three or more prodromal symptoms even after controlling for confounders including previous behavioural symptoms (OR=2.23; 95% CI 1.70-2.94). A dose-response effect was seen. We conclude that cannabis use is associated with prodromal symptoms of psychosis in adolescence.