Summary.The studies concerning the mechanism of the development of hyperphosphatasemia in rabbits with obstructive jaundice have been continued.1 A method is described for the quantitative determination of phosphatase in tissues.2 By means of this method determinations of phosphatase have been carried out on liver tissue, intestinal mucosa and renal cortical tissue from normal rabbits and rabbits on which ductus choledochus has been ligated. 17 to 20 hours after the operation, when the hyperphosphatasemia is maximal it is not possible to demonstrate any difference in the phosphatase contents of liver tissue and intestinal mucosa. In renal cortex a significant fall in phosphatase has been demonstrated.3 The investigations do not give any explanation of the hyperphosphatasemia in rabbits in connection with obstructive jau