The present invention is directed to a nail lacquer consisting essentially of terbinafine as an antimycotic agent, hydroxypropyl chitosan as film forming agent, water and a lower alkanol as solvents. The invention is also directed to a method for treating onychomycosis by topically administering such a nail lacquer to a patient in need of such a treatment.La présente invention concerne un vernis à ongles sensiblement constitué de terbinafine et dun agent antimycotique, dhydroxypropyl chitosane en tant quagent filmogène, deau et dun alcanol inférieur en tant que solvants. Linvention concerne en outre un procédé de traitement dune onychomycose par administration topique dun tel vernis à ongles à un patient nécessitant un tel traitement.