Aim: To describe health-related quality of life of Australian children and adolescents with Down syndrome and compare it with norm-referenced data. Method: A cross-sectional survey was conducted with parents of 75 children and adolescents (43 males, 32 females) with Down syndrome aged 5 to 18 years (mean age 13y 2mo, SD 4y 8mo). The proxy-report KIDSCREEN-27 questionnaire was administered and five dimensions of health-related quality of life were measured. Data were analysed descriptively and compared with normative data. Results: Total group mean scores for psychological well-being, autonomy and parent relation, and school environment dimensions were within normal threshold values, whereas mean scores for physical well-being, and social support and peers dimensions, were poorer. For participants with Down syndrome aged 8 to 18 years, the difference with normative data for proxy-reported physical well-being, psychological well-being, and social support and peers dimensions favoured typically developing children. Adolescents (13-18y) with Down syndrome scored poorer on all dimensions than children (5-12y) with Down syndrome. Interpretation: Our findings assist a better understanding of the lived experiences of children and adolescents with Down syndrome, as perceived by their parents, and suggest aspects of health that could be influenced to optimize their quality of life. What this paper adds: Proxy-reported psychological well-being and autonomy were within the normal range for children with Down syndrome. Physical well-being and social support scores were significantly lower than normative data. Proxy-reported scores for adolescents with Down syndrome were consistently poorer than for children with Down syndrome and the differences were clinically important.