Non-dermatophyte organisms are becoming increasingly prevalent in onychomycosis. This apparent emergence might be an artifact of improved diagnostic techniques and increased awareness that these fungi are potential etiologic agents. It is important to bear in mind that all isolated organisms should be evaluated as potential pathogens when diagnosing fungal infections, especially given the increasing use of immunosuppressive drugs and the increasing numbers of chronically immunocompromised individuals. While many patients with non-dermatophyte mold onychomycosis will respond to oral or topical antifungal therapy, poor or incomplete response might still be expected in some patients.