[Onychomycosis.  Clinico-epidemiological mycological and therapeutic aspects]. 
Onychomycosis is the most frequent cause of nail disease.  Dermatophytic and Candida onychomycosis have a similar frequency (54% and 45%), while only in 1% they are caused by molds.  Tinea unguium equally affects both sexes and is mainly observed in the first toenail.  T. rubrum is the fungus responsible in 87% of dermatophytosis.  The ungual candidosis is three times more frequent on the hands in women and is due to C. albicans in 99% of the cases.  Both types of onychomycosis are observed in children.  Clinical diagnosis of onychomycosis based on direct KOH examination.  Treatment includes the removal of the infested keratin and use of local or systemic antimycotics, such as griseofulvin, ketoconazole and itraconazole.