Study of electrolytic balances in experimental pancreatic necrosis were done on dogs. Acute pancreatic necrosis was produced by injecting olive-oil or bile obtained from the experimental animal into the pancreatic duct. Experimental animals were divided into the two groups, one, in which severe pancreatic necrosis was produced and most of which died shortly after experiment, and the other one, in which mild pancreatic necrosis was produced and all of which survived the experiment. Serum calcium was periodically measured by the phosphate method and serum potassium by the cobalt nitrate method. It was found that serum calcium generally decreased after the onset of pancreatic necrosis. However, it was not always found in the most severe cases, which all died shortly after the experiment, but maximum decrease developed on the third day of the experiment in mild cases and there was found no tendency to return to the level before the experiment. Serum potassium decreased temporarily at the beginning of experimental pancreatic necrosis and then it again increased between 6 and 12 hours later. In the severe group, this increase of serum potassium was marked and animals died at that time. On the other hand, serum potassium returned to the level before the experiment between 12 and 48 hours in the mild group and then it again decreased. The maximum decrease occurred on the third day of experiment and then returned to normal level.