BACKGROUND:Worldwide there is concern that the prevalence of myopia is increasing but the prevalence of myopia in Australian school children has not been analysed in detail. This study examines the prevalence of refractive errors in a large unselected population of primary school children in the eastern suburbs of Sydney. METHODS:Children visiting the Vision Education Centre at the School of Optometry and Vision Science, University of New South Wales, on a school excursion during the first half of the 1990s were refracted by non-cycloplegic retinoscopy. Spherical equivalents were computed and analysis of variance carried out. RESULTS:There were 1,459 boys and 1,076 girls in the study, a total of 2,535 children of whom approximately 40 per cent were born overseas or were first generation Australians. Overall, there was no significant difference in refractive error between girls and boys, although there were age/gender interactions with older girls exhibiting more hyperopia than boys. The refractive error ranged from -0.25 to +1.25 D spherical equivalent in 87.3 per cent of children. Mean spherical equivalent for the group was +0.50 +/- 0.82 D. There was a significant shift (p < 0.001) towards increasing myopia with age. The prevalence of myopia greater than -0.50 D rose from 1.0 per cent of four-year-olds to 8.3 per cent of 12-year-olds. CONCLUSIONS:The prevalence of myopia found in a large multi-ethnic group of non-clinical primary school children in eastern Sydney is lower than expected from other studies in the USA and Asia. Compared with Australian data from the 1970s and 1980s, only a weak increase in the prevalence of myopia is revealed.