Backgrounds : In recent years there has teen renewed interest in the importance of 8-constitution medicine as evidenced by growth of research in this field. Although diagnosis by 8-constitution depends on pulse types, it still is subjective and thus could be insignificant. Therefore, diagnosis based on objective characteristics is essential. Objectives : The purpose of this study was to find objective characteristics of the 4-constitution groups {木(Mok; hepatonia, cholecystonia), {土(To; pancreotonia, gastrotonia), {金(Gum; pulmotonia, colonotonia), {水(Soo; renotonia, vesicotonia)} in 8-constitution for further diagnosis and therapy. Also, some significant clinical tendencies of 4-constitution groups were studied. Methods : From Nov. 2001 to Apr. 2004, data were collected through a questionnaire given to 720 patients who were classified into one of 8 constitutions according to their pulse types and their responses to constitution-based acupuncture therapy. The questionnaire was composed of 80 items which were about personality, physical shape, habit, physiological and pathological symptoms, response to drugs, favorites and responses to various foods. The data were statistically analyzed by cross-tabulation and one-way analysis of variance, and SPSS V10.0.7PC was used. Results : The results are summarized as follows: 1) Among participants, proportions of hepatotonia, pancreotonia, and cholecystotonia were higher than those of vesicotonia, pulmotonia, colonotonia, renotonia, grstrotonia. 2) 52 items of 80 variances showed significant differences by gender, 3) 13 items were highly correlated with 4-constitution groups in males, and 26 items in fremales. 4) 22 items showed significant group differences among 4-constitution groups in males, and 41 items in females. Also, for each item 4-constitution groups were sorted according to their means, so that the constitutional tendencies were objectively figured out by personality, shape, habit, physiological and pathological symptoms, response to drugs, favorites and responses to foods. Conclusions : Most clinical characteristics of 4-constitution groups found in this study coincided with those from the previous ones in this fold. Thus, classifying patients into one of the 4-constitution groups based on significant objective characteristics is of great benefit to diagnosis and therapy. further study should be followed to improve proper therapy for each constitution.