Backgound : Amorolfine is a new topical antifungal drug of the mopholine class which has broad spectrum fungicidal activity. Amorolfine nail lacquer 5% is a transingal delivery system which can penetrate well through the nail plate to the infected keratin and reman here for a prolonged period. Objective : The aim of this study is to assess the efficacy and tole at hty of 5% amorolfine nail lacquer given once weekly to the patients with onychomycosis. Methods : 29 patients with onychomycosis affecting not more that 80% of the surface of nail were treated once weekly for up to 9 months with amorolfine nail lacquer 5%. Clinical and mycological examination were performecl before treatment and 3, 6, 9 months after short of treatment. Final evaluation was done 3 months after the end of treatment. Results : Average affected area(%) and average score of clinical igsthickening, splitting, discoloration were significantly decreased 3 months after start of treatment. Mycological cure rate was continuously increased accorcling to the treatment duration reaching 75.9, at 3 months after treatment. Overall efficacy assessed by the investgators were cure in 31.0 % and improvement in 41.4%. Tolerability, mode and frequency of treatment, and formulation were evoluated as good or excellent by most of the patients. No systemic or local side effect was observed. Conclusion : Amorolfine nail lacquer 5% used once weekly up to 3 onths was relatively effective and safe for the treatment of cnychomycosis. (Kor J Dermatol 1995 3 (2): 314-321)