AIM: This study sought to describe the burden of acute diarrhoeal illness (ADI) in an Australian subtropical urban setting following rotavirus vaccine introduction and to investigate the associations between child/family characteristics and ADI. METHODS: Parents of 154 children from the Observational Research in Childhood Infectious Diseases birth cohort provided daily symptom and health-care data until the age of 2 years. RESULTS: The incidence rate of ADI was 1.07 per child-year (95% confidence interval: 0.94-1.21). The median length of episode duration was 3 days (25th-75th percentiles: 1-6). The incidence rate was significantly higher in the first month of life and between 6 and 17 months of age compared with 18-23 months, also for children with siblings and in formal childcare. Overall, 49% of ADI episodes led to health-care visits. CONCLUSIONS: Despite a successful rotavirus vaccine programme, ADI still results in a substantial disease burden affecting young Australian children and their families.