This study assessed risk factors for respiratory syncytial virus (RSV) hospitalization and disease severity in Wellington, New Zealand. During the southern hemisphere winter months of 2003–2005, 230 infants aged <24 months hospitalized with bronchiolitis were recruited. RSV was identified in 141 (61%) infants. Comparison with data from all live hospital births from the same region (2003–2005) revealed three independent risk factors for RSV hospitalization: birth between February and July [adjusted risk ratio (aRR) 1·62, 95% confidence interval (CI) 1·15–2·29], gestation <37 weeks (aRR 2·29, 95% CI 1·48–3·56) and Māori ethnicity (aRR 3·64, 95% CI 2·27–5·85) or Pacific ethnicity (aRR 3·60, 95% CI 2·14–6·06). The high risk for Māori and Pacific infants was only partially accounted for by other known risk factors. This work highlights the importance of RSV disease in indigenous and minority populations, and identifies the need for further research to develop public health measures that can reduce health disparities.