The authors investigated in articular cartilage the presence and amount of the free fragment of the protein nucleus of the proteoglycan monomer containing the area of the bond with hyaluronic acid (HABR) and the presence of the small dermatan sulfate proteoglycan in relation to age. The articular cartilage of older subjects contains a much higher ratio of the protein fragment with functional HABR, as compared with young adult tissue. The more ready extractability of this fragment suggests an impaired bond between the proteoglycan monomer and hyaluronic acid. The ratio of the small dermatan sulfate proteoglycan is significantly reduced in the articular cartilage of older subjects. In the articular cartilage of a very old person (87 years) this proteoglycan was not detected or its content is at the borderline of detection of the methods used.