Incorporation of labeled glycosaminoglycan polysulfate (35S-GPS) into the knee joint was studied biochemically and autoradiographically. After an injection into a knee joint of a rabbit, 35S-GPS was taken up into articular and meniscus cartilage. A 35S-GPS macromolecule and a complex of 4 M GuHCl extracted soluble substance (mainly considered proteoglycan) exists in the articular and meniscus cartilages. A free sulfate, that is, desulfated 35S-GPS, is not incorporated during proteoglycan synthesis. The 35S-GPS remains longer in meniscus cartilage than in articular cartilage. Immediately after intra-articular administration of 35S-GPS, a high grain count was observed in autoradiographs of the perichondrium and the superficial layer of articular cartilage of rats. One day after injection of 35S-GPS, numerous grains were observed in the deep layer. Autoradiography also demonstrated that 35S-GPS turnover is greater in articular cartilage than in meniscus. Uptake of 35S-GPS in an unmodified form in extracellular matrix of articular cartilage should be further investigated in experimental animals with degenerative osteoarthritis.