One-hundred and ninety-five patients with toenail tinea unguium were recruited to a multicentre double-blind clinical trial. Patients were given 250 mg terbinafine or 200 mg itraconazole daily for 12 weeks, with follow-up for a further 40 weeks, At the end of the study, mycological cure rates were 81% (70/86 assessed) for terbinafine and 63% (53/84 assessed) for itraconazole (two-tailed, P < 0.01), The length of unaffected nail was 9.44mm in the terbinafine group and 7.85mm in the itraconazole group (two-tailed, P < 0.05), Patient self-assessment also favoured terbinafine, with 65% evaluating it as good to very good, compared with 58% for itraconazole. Before treatment the terbinafine group had a mean of 6.7 and the itraconazole group 6.3 affected nails per patient. Total cure was achieved in 69% of terbinafine and 61% of itraconazole affected nails, We conclude that terbinafine is more effective than itraconazole in the treatment of toenail tinea infection.