Acute poststreptococcal glomerulonephritis (APSGN) is an inflammatory kidney condition that can complicate Group A streptococcal infections. Two clusters of APSGN occurred recently in New South Wales (NSW), Australia; one in a rural town in December 1999 and the other in a Sydney suburb in January 2000. We interviewed carers of the affected children but found no common exposures except three of the Sydney cases were cousins in frequent contact. To assess the probability of these clusters occurring, we analysed hospital admissions for acute glomerulonephritis, as a proxy for APSGN in younger patients. The incidence of acute glomerulonephritis in NSW during 1989/90–1997/8 in residents aged under 20 years was 2·2/100000/year (95% CI 2·0–2·5). Incidence was highest in children aged 5–9 years, boys and Aboriginal children. We found no evidence for other clusters during that period. The recent clusters highlight the continued potential for unexpected future outbreaks of APSGN.