Superficial mycoses of the skin (SMSs) are a topical interdisciplinary problem in all countries of the world. The predominant prevalence of skin mycoses in large metropolitan areas makes it possible to call them diseases of civilization. They are detected in 20% of the world population. Dermatophytoses dominate among SMSs, affecting 10% of the population. In this case, dermatophytoses of the feet are detected 3 times more often compared with other localizations. However, mycoses of large skin folds (MLSFs) are an important interdisciplinary issue of medicine. Selection of a therapeutic approach for MLSFs is not a simple task. Ointment-based medications are rarely used, because eruptions are localized in areas with high skin hydration. MLSF may be complicated by a secondary infection and mycotic eczema, particularly with concomitant diabetes mellitus. In connection with this, mycosis proceeds torpidly and is more difficult to treat. Therefore, it is advisable to use topical monotherapies that have the simultaneous pronounced antimycotic, antibacterial and anti-inflammatory effect. One of these medications is sertaconazole cream (Zalain). Objective — to study features of the course of epidermophytosis of large skin folds (ELSF) based on the results of a multicenter study in the Russian Federation and to provide a multivariant analysis of the efficacy of treatment with a topical antimycotic agent (TAA), sertaconazole (Zalain). Material and methods. A multicenter study was conducted in the Russian Federation in 2012—2013 and included 174 doctors from 50 cities. A special version of the questionnaire was developed by the authors to unify the study. There were 2,784 patients with dermatophytoses, including 735 with dermatophytoses of large skin folds. Patients with epidermophytosis of large skin folds (ELSF) (n=615) were predominant. One of the experiment requirements was selection of patients with minimal lesions of the nail plates, when the Sergeev’s scoring clinical index for onychomycosis (SSCIO) allowed only local treatment of foot mycosis. The features of course and the efficacy of treatment of ELSF with sertaconazole (Zalain) were studied on the sample of 235 patients. The results of the multicenter study conducted in Russia revealed the gender characteristics of the disease: more frequent incidence in males (68.3%) and its increase in the age group of 35—55 (48.1%) years. ELSF usually occurs as a multifocal process. Various large skin folds are affected: the inguinal fold, adjacent hip areas, and the marsupium are significantly more often affected in males, and the vulvular lips are affected in females. 1/3rd of patients were detected with foot mycosis and 1/4th with onychomycosis. Sertaconazole (Zalain) used as cream manifested itself as an effective drug for treatment of ELSF, including lesions of the adjacent skin areas, as well as comorbid foot mycosis and minimal onychomycosis. In this case, the recovery period depends on the patient’s age, disease duration, concomitant somatic pathology, previous topical antimycotic therapy, number of skin folds involved in the process, and the presence of foot mycosis, onychomycosis, complications, and mycetogenetic sensitization. In some clinical situations, the duration of therapy with sertaconazole cream can be maximum (about one month).