The author has examined in vitro and in vivo on the influence of photosensitizing dye, Platonin (Thiazolocyanin) upon the activites of cathepsin, glycero-phosphatase, catalase as well as lipase and glyoxalase in the erythrocytes, and obtained the following results. 1) The activities of cathepsin, glycero-phosphatase and lipase of the erythrocytes were added Platonins have increased in vitro, otherwise the activities of catalase and glyoxalase have decreased. The greater the concentration of Platonin become, the more remarkable is the increase or the decrease of the activitces of the said enzymes. 2) In vivo experiment as well as in vitro, the activities of cathepsin, glycero-phosphatase and lipase of erythrocytes was added Platonins have increased, and almost of those of catalase and glyoxalase has decreased, especially in case of addition of pro kg 50 γ Platonin. So it can be said the experiment in vitro and in vivo when added the same decrease of concentration of Platonin; the activities of the said enzymes except lipase is lower the degree of the increase or the decrease by augmentation of times of injection (1-10 times), but the activity of lipase is higher the degree of increase.