The skin mycoses, perticularly dermatophytoses, in Lanzhou district, Northwestern China, was investigated during July 2002-June 2003. The specimens from patients suspected of having dermatomycoses were examined microscopically in KOH preparations and cultured on Sabouraud dextrose agar (SDA). Among 1443 suspected cases, 594 were KOH positive and 221 cultures of fungi were isolated. The most frequently isolated fungi were Trichophyton rubrum (43.9%) Trichophyton mentagrophytes (29.4%) and Candida species (14.0%). The frequency of tinea pedis, onychomycosis and tinea manuum were 38.7, 27.8 and 13.5%, respectively. In Lanzhou district, tinea pedis is the most commonly seen dermatophytoses, and T. rubrum is the most frequent etiologic agent.