This research used data from the Australian Child and Adolescent Survey of Mental Health and Wellbeing to investigate the prevalence of online activity and its impact on mental health disorders and risk taking behaviour. Levels of Internet use (98.9 %) and electronic gaming (85.3 %) were high, and 3.9 % of young people reporting problem behaviour. The proportion of girls with very high levels of psychological distress and problem behaviour (41.8 %) was twice that for boys (19.4 %). Those engaging with a range of risk factors reported higher prevalence of problem behaviour than others. Young people who suffered from emotional problems or high levels of psychological distress spent the most time online or playing games. Internet use was associated with problem behaviour and having attempted suicide, experiencing high to very high levels of psychological distress, using alcohol, and living in a poorly functioning family.