BACKGROUND Tinea gladiatorum as the major health concern among combat athletes and the most common cause of a decrease in the quality of their sports activities. OBJECTIVE This study aimed to determine the molecular epidemiology of tinea gladiatorum in contact sports in Mazandaran Province, Northern Iran. METHODS In total, 631 suspected athletes out of 4240 ones were screened for tinea gladiatorum in this cross-sectional study from May 2018 to February 2019. The infection was confirmed by direct microscopy and culture tests. The causative agents were identified by polymerase chain reaction-restriction fragment length polymorphism method on ITS rDNA region. The indoor environmental factors were evaluated in 81 sports halls in terms of temperature (°C), humidity (%), density (m2 /athletes) and the number of ventilators. RESULTS Tinea gladiatorum was confirmed in 6.5% (278/4240) of the athletes. Tinea corporis was the most common type of tinea (192/278; 69.0%), and 175 cases (27.7%) had more than one type of tinea. Moreover, Trichophyton tonsurans (192/203; 94.5%) was the most aetiological agent in all athletes followed by Microsporum canis (6/203; 2.9%), Trichophyton rubrum (2/203; 0.9%) and Trichophyton interdigitale (1/203; 0.4%). There was no significant association between the prevalence of tinea gladiatorum and the indoor environmental factors. CONCLUSIONS T. tonsurans is the most common agent of tinea gladiatorum in Northern Iran. Since no positive culture of dermatophyte was obtained from mats, it seems that skin-to-skin contact would be the most probable mode of transmission among wrestlers. Accordingly, periodical checkups should be considered by health care providers.