Saliva is used as a biological fluid to replace the blood in some clinical diagnoses. To get the saliva is more convenient and easier than that of blood. The present study is to investigate whether the blood can be substituted by saliva to determine the concentration of lactate, creatinine, blood urea nitrogen and uric acid. 18 students (10 female, 8 male) participated in this study. Saliva and blood samples were collected in the same time. Samples were analyzed by a dry-type blood analyzer, which was the most frequently used blood analyzer in Taiwan sports society. Our study showed good correlation of lactate (r=0.85) and creatinine (r=0.77) and lower correlation of blood urea nitrogen and uric acid between saliva and blood. Therefore, saliva may be used as an alternative fluid to determine the lactate and creatinine.