To identify the relation between simple reaction time and height and arm length, simple reaction time was performed to medical students with measurement of height, and arm length. Participants should answer questions about Smoking, drinking, sleep deprivation, history of diseaseand drug, whether to use computer or hot Mean height of men(n=98) was 173.0+/-4.79 cm, that of women (n-22) 161.7+/-4.33 cm. Mean arm length of men was 73.5+/-3.09 cm, and that of women 68.0+/-2.93 cm respectively. Height and arm length were statistically significantly different between-men and women (plt;0.01). Mean simple reaction time of men was 265.4+/-25.03 msec, that of women 286.8+/-28.48 msec. Mean simple reaction time was also statistically significantly different(p<0.01). As a result of correlation analysis, for men. None was significant. However, for women, height and arm length showed statistically significant, correlation with mean reaction time. Correlation coefficient of height and arm length were 0.45 (p<0.05) and 10.57 (p<0.05) respectively.