Chondroitin sulfates and other glycosaminoglycans are administered as drugs to man by intravenous, intramuscular or oral routes. There are some studies on the pharmacokinetics of heparin, heparan sulfate and dermatan sulfate, whereas few data are available on the metabolic fate of chondroitin sulfate in man. Partially depolymerized chondroitin sulfate (mean mol. wt: 7.5 kd, range 5-10 kd) with a ratio of 1:3 between chondroitin-4-sulfate and chondroitin-6-sulfate has been administered as single administrations of 0.2 and 1.2 g by intramuscular and oral routes respectively to 10 healthy volunteers (5 males and 5 females), aging 25-53 years. After intramuscular administration the plasma level increased to a concentration peak at 90 min. The peak concentration, the elimination half-life and the apparent distribution volume were respectively 3.8 mcg/ml, 275 min and 0.40 ml/g. About 37% of the administered chondroitin sulfate is excreted in the urine during the first 24 h as high- and low-molecular-weight derivatives. After oral administration the concentration peak was observed at 240 min. The concentration at the peak, the elimination half-life and the apparent distribution volume were respectively 4.6 mcg/ml, 310 min and 0.44 ml/g. A peak of mono-, oligo- and polysaccharides with a molecular weight lower than 5 kd derived from partial digestion of exogenous chondroitin sulfate is also present in plasma. This study shows that about 10% and 20% of the orally administered drug is absorbed as high- and low-molecular-weight derivatives respectively. Comparison with the results obtained in experimental animals indicate that the metabolic fate of partially depolymerized chondroitin sulfate is similar in man and in experimental animals.