Onychomycosis is the most common nail disease and its prevalence in the literature is estimated between 18 and 50%. The main objective of this study is to describe the epidemiology of onychomycosis and specify the most frequently fungal agents isolated at the University Hospital of Casablanca. Materiel and methods. - In a retrospective study, performed at the laboratory of Parasitology and Mycology, University Hospital Center of Casablanca (Morocco), over a period of 5 years (2006-2010), mycological results (microscopic study and culture) of 2070 nail samples made during this period were analysed. All onychomycosis cases included in this study had positive microscopy and culture. Results. - Totally, during this period, mycological aetiology was confirmed in 64.5% of cases. Dermatophytes were isolated in 65% of cases (n = 858), yeasts in 30% (n = 405) and molds from 72 nails. Candida albicans is the predominant yeast species in this study (49%), essentially in the fingernails. Onyxis in toenails is essentially dermatophytic, and Trichophyton rubrum is isolated in 75% of onychomycosis of foot. Conclusion. - Onychomycosis is a frequent disease in our context, due to diversified fungal agents: dermatophytis in toenail and Candida at the fingernails. (C) 2012 Elsevier Masson SAS. All rights reserved.