Duration of therapy is an important factor in determining patients' compliance in dermatomycosis. Terbinafine (Lamisil) is an allylamine antifungal agent. Its fungicidal properties against dermatophytes should allow physicians to reduce treatment duration without affecting the cure rate. This study was carried out to determine the efficacy and tolerability of terbinafine 1% cream, applied once daily for 7 days, in adult patients with tinea corporis/cruris. In a multicentre, randomized, double-blind, parallel-group study, patients with a clinical diagnosis of tinea corporis/cruris confirmed by microscopy and culture received treatment with either terbinafine 1% cream (n = 57) or placebo cream (n = 60). The patients applied the cream once daily for 7 days, and were then observed for a further 7 weeks. The efficacy was assessed at the end of the study by comparing the rates of mycological cure in the two treatment groups. Total clinical signs and symptoms scores, clinical response, and overall treatment efficacy were also measured and compared between the two groups. A 7-day once-daily course of terbinafine was significantly more effective than placebo in achieving and maintaining mycological cure (84.2 versus 23.3%, P< 0.001). Terbinafine was also significantly more effective than placebo in terms of clinical response, reduction in signs and symptoms scores, and overall efficacy. The short treatment regimen and the sustained high cure rate should contribute to making terbinafine a valuable treatment option in tinea corporis/cruris.