A study was conducted to clarify the characteristics of urinary 3-methylhistidine (3-Me),urea-nitrogen (Urea-N) and creatinine (Cr) excretion on athletes during exercise training period.Experiments were performed on 30 athletes (the group of athletes included 9 long distance runners as training for aerobic performance (Runner), 9 short distance runners as tranining for anaerobic performance (Sprinter), 12 rugby football players as training for aerobic and anaerobic performance (Rugger)) and 11 sedentary controls (Control). The subjects ingested a meat-free diet for 4 days. For analysis of urinary 3-Me, Urea-N and Cr in subjects, urine sample over a 24-h period were collected on fourth day of meat-free diet period. The main results obtained were as followed: 1) Urinary 3-Me and 3-Me to Cr ratio found in athletes were significantly higher than that found in Control. However, a similar Urea-N to Cr ratio was found in Control and athletes except Runner. 2) In Sprinter, 3-Me to Cr ratio was significantly higher than that found in the other groups, but there was no significant correlations between 3-Me and Cr. 3) In Runner, Urea-N to Cr ratio was significantly higher than that found in the other groups, but there was no significant correlations between Urea-N and Cr. 4) In Rugger, 3-Me, Urea-N and Cr tended to be higher than that found in the other groups,but 3-Me to Cr and Urea-N to Cr ratios were similar to that found in Runner and Sprinter,respectively. The significant correlations between 3-Me and Cr and between Urea-N and Cr were observed similarly in Rugger as found for Control. These results suggest that urinary indices of protein catabolism is dependent on the types of chronic exercise training in athletes.