Euglobulin fraction of human plasma was extracted with 0.01 M phosphate buffer (pH 7.3) (PB) containing 1 M NaCl. The substances in the extract were separated by DEAE-cellulose column chromatography into two uronic acid-containing fractions (0.5 Fr and 0.75 Fr). The major fraction (0.75 Fr) was eluted at the void volume in gel filtration on Sephadex G-200, yielding 0.75-G Fr. 0.5 Fr and 0.75 Fr and their pronase digestion products (0.5-P Fr and 0.75-P Fr) together with 0.75-G Fr were examined by electrophoresis on cellulose acetate membrane. The results of electrophoresis and the digestibility with mucopolysaccharidases of these fractions indicated that 0.5 Fr and 0.75 Fr contained proteochondroitin sulfate A. It is suggested that chondroitin sulfate A in 0.5 Fr might be less sulfated than that in 0.75 Fr. Furthermore, analytical data and the infrared spectrum of 0.75-G Fr supported the above view.