The glycosaminoglycans in human cementum have been studied. Following proteolytic digestion of guanidine/EDTA and collagenase extracts of cementum, glycosaminoglycans were isolated and then separated by cellulose acetate membrane electrophoresis. After specific elimination by enzymatic and chemical treatments the glycosaminoglycans were identified as hyaluronic acid, chondroitin sulfate and dermatan sulfate. Neither heparan sulfate nor keratan sulfate were observed. Quantitation of the glycosaminoglycans in both extracts revealed chondroitin sulfate to represent the major species present. Hyaluronic acid was observed predominantly in the guanidine/EDTA extract while dermatan sulfate was a quantitative minor component of both extracts.