Dermatomycoses are an important sanitary problem. Our country counts with partial epidemiological data only referred to a few geographical areas. The aim of our work was to perform a multicenter study with the participation of 15 medical centers located at the Capital City and in 11 Provinces of Argentina with different socioeconomical and cultural characteristics. Between October and December 1998, 851 ambulatory patients of both sexes (58% female, 42% male) with lesions compatible with mycoses in skin, nails or scalp were studied. Only 51.6% of the patients had mycoses confirmed by direct microscopic examination and/ or culture. Dermatophytes caused 69.3% of the diagnosticated infections, yeast 12.2% and Malassezia furfur 13.3%. Agents of dermatomycoses most frequently isolated were T. rubrum (52.7%), T. mentagrophytes (19.2%) and M. canis (14.2%). C. albicans was the predominant causative agent of yeast infections (44.4%). In children below 11 years old, the most frequent infections were tinea capitis 55.4% (M. canis 60%, T. tonsurans and M. gypseum 8.3%) and tinea corporis 20% (M. canis 46%, T. mentagrophytes 30%). The most frequent localizations in adult were toenail and feet (63%) (T. rubrum 47.3% and 45.7%, T. mentagrophytes 9.5% and 23.4%, respectively), fingernail 15.6% (C. albicans 25% and T. rubrum 8.3%) and trunk and extremities 12.2% (M. furfur 57.5% and T. mentagrophytes 14.9%). Direct examination allowed the diagnosis of 94.66% of all positive samples and 91.74% of the cases with positive isolation.