Kimitsu Chuo Hospital is located in the middle of Chiba Prefecture along Tokyo Bay. An epidemiological survey of dermatophytosis was made at the dermatology clinic of the hospital from January 1994 through December 1999. Dermatophytosis patients numbered 2,580 and disease types were composed of: tinea pedis 1,656 (64.2%), tinea unguium 377 (14.6%), tinea corporis 308 (11.9%), tinea cruris 139 (5.4%), tinea manuum 92 (3.6%), tinea capitis 6 (0.2%) and tinea profunda 2 (0.1%). Species frequencies in the 1,610 strains isolated from these patients were as follows: 929 (57.7%) of Trichophyton rubrum, 651 (40.4%) of T. mentagrophytes, 9 (0.6%) of Microsporum gypseum, 8 (0.5%) of M. canis, 8 (0.5%) of Epidermophyton floccosum and 5 (0.3%) of T. violaceum. The ratio of T.R/T.M was 1.43 in all the isolates, and 0.81 in the isolates from tinea pedis. These ratios were lower than those of the epidemiological survey of dermatomycoses in Japan in 1997. T. mentagrophytes was characteristically dominant in this hospital and resulted from a drastic increase in tinea pedis caused by this species in the summer season.