Disposable soft contact lenses have been marketed as a safer alternative to conventional soft lenses. We undertook a case-control study of patients attending the casualty unit of an eye hospital to quantify the relative risk of keratitis in disposable lens wear and to establish associated patterns of use. All eligible contact lens users were identified and asked to complete a questionnaire (n=242). Keratitis, microbial or sterile, was the most common complication in disposable lens users, occurring in 16 of 41 subjects. The relative risks for all lens types were estimated by comparison with rigid lenses (the referent). Both extended- and daily-wear disposable lenses were associated with higher risks of keratitis than other lens types including conventional extended-wear lenses. Poor hygiene, disinfectant system failure, and lens type may all account for these statistically significant trends.