The effect of supplemental dietary arginine on dynamic changes in peripheral blood Th/ Ts ratio and survival rate were studied in burned rats (30% TBSA III degree). The results are as follows: 1. Th/Ts ratio dropped on the 3rd day and showed a trough value 10 days postburn. 2. Arginine could prevent the falling of Th/Ts ratio, which was distinct since 5 days after burn. 3. Survival rate 14 days postburn was raised in arginine rats. This study suggests that dietary arginine may be beneficial after severe burn.