OBJECTIVE To determine the incidence of fair eye and its determinants. DESIGN Inventory and case referent study. METHOD All general practices (370) in the middle and south of Limburg, the Netherlands, were asked to report patients with a 'faireye' after having visited a fair in this region (population approximately 866,000) in a 6-week period during the late summer of 1997. Personal data of these patients were obtained by telephone interview. A case referent study was performed to establish the potential protectiveness of wearing glasses, lenses or a cap. RESULTS 88% of the general practices responded. These reported a total of 40 patients with a fair eye. There were 41 fairs with dodgem cars during the observation period (a relation between dodgem cars and faireyes has been suggested). In the study area the incidence of fair eye was 5 per 100,000 inhabitants per year. Of the 36 responding patients 26 (72%) were male, 97% were 10-19 years old, and 69% had had 11-20 rides in dodgem cars. Glasses (3%), lenses (0%), or a cap (6%) were rarely worn during the rides. The complaints related to the fair eye were: pain in the eye (64%), an irritated eye (42%), a red eye (41%), an inflamed eye (17%), tears (11%) and photophobia (8%). The odds ratio for wearing glasses or lenses in comparison with a sample of the general Dutch population, standardised for age and sex, was 0.1 (95% confidence interval: 0.01-0.69). CONCLUSION With 5 per 100,000 inhabitants per year fair eye is a regular complaint in general practice in South and Middle Limburg. The metal particles involved probably come from dodgem attractions, which usually move weekly to another town or village between March and November. Wearing glasses or lenses is rare in patients with fair eyes. It is advisable to wear protective goggles when riding dodgem cars.