A multicentre, prospective, randomized, double-blind, parallel group study was undertaken to compare the efficacy and tolerability of topical terbinafine with topical clotrimazole in the treatment of interdigital tinea pedis. Patients were randomized to receive either terbinafine 1% cream twice daily for 1 week, followed by a similar placebo cream for 5 weeks, or clotrimazole 1% cream twice daily for 4 weeks. Outcome measures were: (i) mycological cure (negative culture); (ii) effective treatment (negative culture plus a symptom score of 2 or less out of a maximum score of 18); and (iii) complete cure (negative culture and a symptom score of 0); measured at 1, 4, 8 and 12 weeks after the commencement of the study. One hundred and four of the 217 patients randomized had a culture-confirmed dermatophyte infection at baseline. In these patients, 84.6% in the terbinafine group were culture negative after 1 week, compared with only 55.8% in the clotrimazole group. Both agents were well tolerated. The study showed that terbinafine achieves mycological cure more rapidly than clotrimazole. This may result in improved compliance and better control over transmission of infection.