Onychomycosis is a fungal infection of nails caused by dermatophytes, yeasts or non-dermatophyte molds. The aim of our study was to describe the epidemiological features of onychomycoses encountered in the Tunis region. A retrospective study concerned 3458 cases of onychomycosis, confirmed by direct examination and/or a positive culture, was conducted in Parasitology – Mycology Laboratory, Rabta hospital, over a five-year period (2012–2016). Our patients were aged 1 to 85; more than half of the patients were aged over 60 years with a female predominance (67%). Toenail infections were most common, observed in 2702 cases (78%). Direct examination was positive in 3284 cases (95%), culture in 2409 cases (69.6%); these two examinations were positive simultaneously in 2235 cases (64.6%). The causative agents of these onychomycoses were dominated by the genus Candida in fingernails: Candida albicans (55.6%), Candida tropicalis (8.5%) and Candida parapsilosis (8.2%) were the most frequently incriminated species; while in toenail lesions, Trichophyton rubrum was by far the most frequently isolated species (96.8%). Our results join the literature; onychomycosis is a pathology of the adult, mainly candidosic etiology in hands and dermatophytic in feet.