The utilization of glucose by red blood cells declines considerably in shock and after trauma. The decrease intensifies with the increasing intensity of trauma. Simultaneously the level of lactic acid in the blood of traumatized animals increases. The glycolytic activity decreases in samples with lactic acid added but not in cases of added sodium lactate. The decrease in glycolytic activity of red blood cells is caused by the shift of acid-base equilibrium to the acid site. During shock pH of arterial and venous blood falls considerably and simultaneously the utilization of glucose by red blood cells decreases.