The turnover of sulfate label in crude glycosaminoglycan fractions from rat kidney cortex, medulla, and papilla has been determined. Heparan sulfate, chondroitin sulfate, dermatan sulfate, and hyaluronate have been separated electrophoretically and their specific activities determined after injection of labeled sulfate or glucose. The half-lives of the sulfated glycosaminoglycans are within the ranges found for other organs and tissues, but hyaluronate has a somewhat faster turnover in the kidney than elsewhere.