To determine the incidence of childhood onset type 1 diabetes in Australia from 2002 to 2017, and analyse incidence rate trends by calendar year, sex and age at diagnosis. Children newly diagnosed with type 1 diabetes aged <15years between 2002 and 2017 were identified from the National Diabetes Register, estimated as ~99% complete. Data were obtained for diagnosis year, sex, age and residential State/Territory at time of diagnosis. Population estimates by year, sex, single year of age and State/Territory were obtained from the Australian Bureau of Statistics and Poisson regression used to examine incidence and trends by calendar year, sex and age group at diagnosis. Between 2002 and 2017, there were 16,783 newly diagnosed cases of type 1 diabetes in children aged <15years (8,684 boys: 8,099 girls), giving a mean incidence of 25.0/100,000 person years (95%CI:24.6,25.4). A sinusoidal pattern in the incidence rate trend was observed with 5-yearly cycles providing the best model fit. No significant difference was observed in boys compared to girls (IRR 0.98(95%CI:0.95-1.01)). Compared to 0-4 year olds, the mean incidence was 75% higher in 5-9 year olds, and 224% higher in 10-14 year olds. A decreasing incidence rate trend was observed in 0-4 year old boys and girls. This study reports updated incidence and incidence rate trends in children and adolescents diagnosed with type 1 diabetes in Australia. A cyclical pattern in incidence trend persists, with an overall decreasing trend observed only in the youngest age group.