0.1 ml. of the 1% solution of chondroitin sulfate labeled with S(35) was administered to mice intraperitoneally or 0.5 ml. was given per orally with gastric tube to another gronp of mice. Each two mice were killed every one, two, six, twelve, twenty four and fouty eight hours after the injection respectively and after a series of daily injection for a week samples of blood, lungs, heart, liver, kidneys, skin, muscles bones, spleen, brain, stomach and ntestines were taken from these animals. Radioactivity of S(35) was measured by BaSO(4) method using Lanritsen's electroscope. 1) The highest activity in blood was observed by about two hours after the injection, while in per oral administration it was reached after six hours. absorption of perorally administered chondroitin sulfate was estimated to reach roughly 35% abter 6 hours. 2) The excretion of labeled chondroitin sulfate seemed to be done from kidneys. The greater part was excreted in six hours and then the decrease in the activity of kidneys became slower. 3) Muscles and skin showed a considerable activity in 1-2 hours. A marked decrease was seen after six hours, then their activity seemed to remain unchanged. 4) Radioactivity of skeleton rose gradually, reached its maximum in twelve hours, and then had a tendency to show constant value. 5) In liver, spleen and brain highest activity was observed two hours after the injection.