Gendered power imbalances in heterosexual relationships are a key target of gender-sensitive STI risk reduction interventions. Gendered aspects of sexual behaviour have not been explored among Canadian indigenous young people, who are at elevated risk for STI relative to other young Canadians. We used data from in-depth qualitative interviews with 15 male and 15 female indigenous young people to explore gendered sexual behaviour and its implications for STI reduction. There was a pervasive 'double standard' where young men were expected to be sexually aggressive and young women were expected to resist sexual advances; but we also observed 'alternative' or non-hegemonic behaviours. Specifically, young women were often very active participants in sexual negotiations, could refuse condom use and sometimes pressured their male partners to not use condoms. Young men also described being the object of coerced sex, and did not always perceive female sexual desire in negative terms, and were not always receptive to sex. The gendered sexual attitudes and behaviours in our sample were much more complex than usually described in the literature. Intervention work needs to take more realistic account of the sexual interactions that occur between young people.