In a multicentre double-blind randomized parallel-group study, 31 patients who had mycologically proven tinea corporis or tinea cruris were treated topically with either terbinafine 1% cream or its vehicle, applied once daily for 1 week. The percentage of patients 'effectively treated' (combined mycological and clinical outcome) was 86% for terbinafine compared with 35% for placebo (P = 0.01, Fisher's Exact test, two tailed). No adverse events were reported during the study. Topical terbinafine 1% cream used once daily for 1 week is an effective and well-tolerated treatment for tinea corporis and tinea cruris.