Objective : Hyperhidrosis is the secretion of sweat in amounts greater than physiologically needed for thermoregulation. Ryodoraku is a physiological function test using electric current, and is closely related to skin sympathetic tone. The aim of this study was to investigate the characteristics of Ryodoraku and association of Ryodoraku with hyperhidrosis. Methods : For this study, we conducted Ryodoraku on 56 people, comprising 33 with palmar-plantar hyperhidrosis and 23 with head-face hyperhidrosis, who visited the 5th Internal Department of the Oriental Medicine Hospital of Kyung Hee University during the period from March 1, 2008 to May 31, 2009. Ryodoraku scores were evaluated and compared by 7 indices(upper, lower, left, right, yin, yang, total score). Results : Ryodoraku scores were significantly higher in hyperhidrosis patients than the normal group. Ryodoraku scores of palmar-plantar hyperhidrosis patients were significantly higher than of head-face hyperhidrosis patients and the normal group. The difference of Ryodoraku indices among palmar-plantar hyperhidrosis patients were insignificant. In head-face hyperhidrosis patients, the upper index was significant higher than the lower index. Conclusions : In hyperhidrosis patients, all indices were significant higher than lower. The upper/lower ratio was significant higher in head-face hyperhidrosis patients.