BACKGROUND: The dermatophytes are important in the Swiss medical environment since 5-10% of consultations in dermatology concern mycotic infections. OBJECTIVE: To obtain information about the prevailing species of dermatophytes in the south-west of Switzerland and their pattern of infection. METHODS: An analysis was made of the dermatophytes isolated in the Department of Dermatology at the University Hospital of Lausanne and from samples collected in private practices of Switzerland during an 8-year period (1993-2000). The total number of samples sent for mycological analysis was 33,725. RESULTS: 4,193 cultures revealed a dermatophyte. Trichophyton rubrum was the most frequently isolated species accounting for 62.5% of the strains followed by T. mentagrophytes (24.5%) and Microsporum canis (5.0%). Less frequent isolates included Epidermophyton floccosum, M. langeroni, M. gypseum, T. soudanense, T. violaceum, T. verrucosum, T. gourvili and T. tonsurans. Analysis of the localisation of the isolated fungi confirms that the dermatophyte species have a predilection for certain body areas. CONCLUSIONS: The relative frequencies of isolation of the dermatophyte species partially depending of the record of the different tinea vary from one country to another. Our study reveals the importance of T. rubrum and the appreciable frequency of M. canis in the Swiss autochthonous population and the apparition of new species with immigrants.