Objective: To review whether oral terbinafine, used for fungal nail infections, is prescribed appropriately by general practitioners Method: Cross‐sectional survey of forty volunteer practices. Prescribing systems were searched to identify patients who had been prescribed a course of oral terbinafine during 1998. The clinical records of five such patients in each practice were examined for additional information regarding appropriate diagnostic tests.Results: Five hundred sixty‐nine patients (0.25% of the population aged 12 and over) were reported to have received a course of oral terbinafine. Sixty‐four percent had been treated empirically without any recorded diagnostic test.Conclusion: Treatment of onychomycosis with terbinafine is commonly undertaken without diagnostic confirmation. This empirical treatment does not comply with locally recommended good practice.