AIM: Previous studies have consistently reported high rates of risky behaviour for sexually transmitted infections (STIs) amongst individuals with persistent psychosis. Whether such behaviours are evident from the first presentation or relate to a chronic illness course remains largely undetermined, with limited research conducted amongst young people with first episode psychosis. The aim of the current study was to compare engagement in sexual risk behaviour amongst young people with first episode psychosis with their peers. METHODS: Sixty-seven sexually active young people with first episode psychosis and 48 healthy control participants (aged 18-29 years) closely matched on sociodemographic characteristics completed a detailed questionnaire assessing a comprehensive range of sexual risk behaviours. RESULTS: There were few differences in the rates of sexual risk behaviour reported by the first episode sample and their peers. Compared with control participants, young people with first episode psychosis reported significantly more inconsistent condom use, less condom-related preparatory behaviour, more concern about HIV/STIs when sex was unprotected, less confidence discussing condom use and increased substance use by their last sexual partner. CONCLUSIONS: The sexual behaviour of young people with first episode psychosis appears similar to their peers. However, group differences, particularly increased frequency of unprotected sex amongst the first episode sample, suggest that those with psychosis are at increased STI risk and have distinct needs. The findings support the call for early intervention strategies that target reduction of sexual risk behaviour in the context of persistent mental illness.