In order to investigate the cause of the toxic action of the parenchymatous poisoning which are represented by arsenic and phosphor poisoning, enzymochemical studies on the influences of the parenchymatous poisoning to the activities of cathepsin, phcsphatase and amylase in the organs and serum have been attempad, and the following results were obtained by the experiments of Rep. I, 2 and 3. Rep. I: Uuder the arsenic poisoning, the serum albumin decreased and the activity of cathepsin in the liver was inhibited, but the serum γ-globulin increased and the activity of cathepsin in the serum was strengthened. Rep. 2: The activity of phosphatase in the brain, heart, lung, liver, kidney and serum was inhibited under the acute arsenic poisoning, but the activity of phosphatase in the serum and the organs except the heart were slightly strengthened under the chronic poisoning. Rep. 3: The activity of amylase in the brain, heart, lung, liver, kindey and serum were inhibited slightly under the acute arsenic poisoning, but under the suba_ute and chronic poisoning, the activity of amylase were strengthened obviously, especially in the lung, kidney and heart.