Four cases of invasion of fingernails caused by Fusarium oxysporum are described. The typical picture of onychomycosis by this non-dermatophytic mould is a 'white superficial onychomycosis' which usually affects the great toenail. Only few cases of fingernail infections by this organism have been described in the literature and, to our knowledge, there are no reported cases on the pustulous and eczema-like aspect of paronychia by Fusarium oxysporum. We report different and unusual clinical features of this infection successfully treated with systemic antifungals. Two patients were treated with terbinafine, 250 mg daily for 3 months, and two patients with itraconazole, 200 mg daily for 3 months.