A case of fingernail infection by Fusarium is presented. This nondermatophy
tic mold is an infrequent cause of onychomycosis, more typically involving
the great toenail. Characteristic histologic features including the presenc
e of hyphae and chlamydoconia are helpful in rapid diagnosis and selection
of appropriate antifungal therapy. Although Fusarium has shown resistance t
o most antifungal medications in vitro, intermittent therapy with fluconazo
le led to improvement in this patient.