The present study dealt with the effect of intensity of exercise on the transient changes in urinary and dermal nitrogen losses. Six healthy men served as the subjects. The experiment consisted of four consecutive days, pre-control day, control day (C), 60% VO2max exercise day (60% E) and 80% VO2max exercise day (80% E). Exercise was loaded for 40min with bicycle ergometer at the intensity of 60% or 80% of VO2max during exercise period (from 9: 00 to 11: 00). Urinary nitrogen excretion was depressed, while dermal nitrogen loss was elevated by exercise loading, especially in 80% E. During recovery period (from 11: 00 to 19: 00), higher urinary excretion was observed in 80% E than in C or 60% E, but no significant difference in dermal nitrogen loss was observed in C, 60% E and 80% E. The sum of the urinary nitrogen excretion and the dermal nitrogen loss from 9: 00 to 19: 00, including both exercise and recovery period, was higher in 80% E than in C or 60% E.