The National Rotavirus Reference Centre together with collaborating laboratories Australia-wide has conducted rotavirus surveillance since June 1999. This report describes the serotypes of rotavirus strains responsible for the hospitalisation of children with acute gastroenteritis during the period 1 July 2004 to 30 June 2005. Six hundred and twelve faecal samples from across Australia were examined using monoclonal antibody immunoassays, reverse transcription-polymerase chain reaction and polyacrylamide gel analysis. Serotype G1 was the dominant serotype nationally, representing 48.3 per cent of all strains, followed by serotype G3 (36.7%) and serotype G9 (6.9%). As in previous years, there was substantial geographic variation in the prevalence of rotavirus serotypes.