Proximal white subungual onychomycosis (PWSO) is a rare form of onychomycosis of both fingernails and toenails. It occurs when the fungus invades the stratum corneum of the proximal nailfold followed by infection of the deeper parts of the nail plate. The surface of the overlying nail is usually normal. A case of PWSO is described with complete cure by the use of oral terbinafine 250 mg/day for 3 months continuously.