Studies were made of the chemical changes in the blood of 29 dogs which had been subjected to mild trauma of the muscles while under ether anesthesia. The dogs succumbed in secondary shock in 3-17 hrs. The condition was characterized by a slight decrease or no change in the red cell conc. a slight decrease in the Cl conc. and no consistent change in the water content of the plasma. Following the K-lowering effect of the anesthetic the plasma K rose significantly, although in a variable manner, during the 2d 40% of the survival time; the avg. increase was 19%. (greatest increase 80% ), whereas in the controls an avg. decrease of 0.6% was found. Just prior to death an increase of 100-200% occurred. Analyses of the injured muscle and of the fluid found at the site of injury indicated that K was liberated from muscle cells as a result of the traumatization. Local fluid loss and not the high K conc. was considered to be the major, although not the sole cause of death, since the vol. increase of the traumatized limbs averaged 40% (range 13-71) of the blood vol.