Chondroitin sulfates proteoglycans were isolated from human placenta. For the identification of enzymatic digestion products of isolated proteoglycan, strong anion exchange-high performance liquid chromatography (SAX-HPLC) was performed. By the action of chondroitin ABC and chondroitin B lyase, three unsaturated disaccharides 2-acetamide-2-deoxy-3-O-($eta$-D-gluco-4-enepyranosyluronic acid)-D-galactose ($delta$Di-OS), 2-acetamide-2-deoxy-3-O-($eta$-D-gluco-4-enepyranosyluronic acid)-6-O-su lfo-D-galactose ($delta$Di-6S) and 2-acetamide-2-deoxy-3-O-($eta$-D-gl uco-4-enepyranosyluronic acid)-4-O-sulfo-D-galactose ($delta$Di-4S) were produced from the human placenta proteoglycan. The anticoagulant activity of chondroitin sulfate proteoglycan was evaluated by activated partial thromboplastin time (aPTT) assay and thrombin time (TT) assay. The clotting times of aPTT and TT were increased from 72 to 144 sec and 19 to 27 sec, respectively. The Immune-modulating activity of chondroitin sulfate proteoglycan was examined by cell proliferation assay and these results suggest that it may play a role in suppression of the function of immune-related cells.