The purpose of this study is to determine that YMCA step-test is useful method of cardiovascular fitness field-test for large scale study of epidemiology. 57 adults participated in this study. They are recruited considering subject's clinic status and gender proportion. Cardiorespiratory fitness of each participant was determined by grade exercise testing(GXT) with gas analysis and YMCA step-test. There are at least more two days an interval between the tests. Data were analyzed with a statistics program, SPSS version 14.0, by applying Spearman correlation coefficient and independent t-test and Fisher's exact test with a statistical significant level of alpha<.05. The results of this study were as followed. VO2max value exhibited significant correlation with YMCA step test scale(male : r =-.611, p=.001 ; female: r=-.656, p>.001). Our result is that validity of YMCA step-test is acceptable. YMCA step test is vary efficient as dimension of investigator's and subject's effort then the other field-test for assessment of cardiorespiratory. Therefore, Step test is useful for large scale study of epidemiology.