Background: The incidence and causative dermatophytes of tinea cruris has been changed with time. Although clinical and mycologic studies of whole dermatophytosis have been reported many times, there have been only a few studies about tinea cruris reported. Objective: The purpose of this study was to investigate clinical and mycological features of tinea cruuis. Methods: We evaluated the clinical and mycologic aspects of tinea cruris in 598 patients with tinea cruris from January 1985 to December 1997 in Yeungnam University Hospital. Results: The incidence of tinea cruris was 20.8% of 2,878 total dermatophytoses. The ratio of male to female patients was 23.9:1. And most of them were in their twenties and thirties. Most(82.1%) of them involved both sites of the groin. Concurrent dermatophytic infections of tinea cruris were noted in 29.4% of the cases and the most common one was tinea pedis(22.4%). Three hundred and thirty eight dermatophytes were isolated from 598 patients with tinea cruris. They were Trichophyton(T.) rubrum(95.3%), T. mentagrophytes(4.4%), Epidermophyton floccosum(1.2%), Microsporum canis(0.9%). Conclusion: Tinea cruris is a male predominant dermatophytosis, the most common causative organism is T. rubrum, and tinea pedis seems to be an important reservoir. (Korean J Dermatol 1999;37(2) :. 219-224)