Amorolfine is a new topical antifungal of the phenylpropyl morpholine class which is highly active both in vitro and in vivo against yeasts, dermatophytes and moulds responsible for superficial fungal infections. Human pharmacological studies have established that amorolfine has a persistent antifungal effect in the nail bed and in the skin without being systemically absorbed. This has been confirmed by clinical work showing that amorolfine is effective in treating dermatomycoses and onychomycoses when administered as cream or nail lacquer. It is ineffective when given orally for systemic mycoses or bacterial infections in animals. In earlier studies a 5% concentration of amorolfine nail lacquer was found to produce a better cure rate in onychomycosis than a lower concentration of 2%. From data available on the penetration of amorolfine and on the persistence of mycologically relevant tissue concentrations, it appeared likely that once- or twice-weekly application of nail lacquer should suffice to produce a satisfactory therapeutic effect in onychomycosis. The aim of this investigation was to assess the efficacy and tolerability of 5% amorolfine nail lacquer given once versus twice weekly to patients with onychomycosis of finger nails and toe nails.