The changes in erythrocyte deformability and os moti c fragility were studied with an animal model of mild burn injury. The results s howed that after the burn injury there was a gradual decrease with time at first and then a recovery in erythrocyte deformability. Maximum deformation index ［(DI)max］, integra tion deformation index (IDI) and osmotic fragility of RBCs drawn just after burn were almost identical to those before burn injury. (DI)max and IDI signifi cantly decreased at 1, 2 h but not at 4, 7 h when compared with those before burn injury, however, the RBCs were less deformable at 4, 7 h. Erythrocyte osmotic fragility significantly increased only at 4 h after burn injury when compared at the time points of 0, 1, 2, 4 , 7 h after burn with that before burn injury. The results indicated that the lesion in (DI)max and IDI, and the increase in osmotic fragility might be only related to the body fluid fa ctors in this animal model. The decrease in erythrocyte deformability and the in crease in erythrocyte osmotic fragility did not synchronize, suggesting that the changes might come about not by the same mechanism.