The semilunar meniscal body, horns and peripheral attachment were dissected from human and canine knee joints. The concentrations of hyaluronate, chondroitin sulfate, dermatan sulfate and keratan sulfate differed markedly among the tissues. The meniscal body was fibrocartilaginous but showed marked histological microheterogeneity with hyalinized areas intermixed with fibrous areas and contained mostly chondroitin sulfate and keratan sulfate. On the other hand, the fibrous peripheral attachment contained mostly dermatan sulfate and hyaluronate and almost no keratan sulfate and the ligamentous horns contained mostly dermatan sulfate and chondroitin sulfate. Human menisci contained more dermatan sulfate and less chondroitin sulfate than did canine menisci. From morphometric measurements of canine menisci, an estimate was made of the amount of peripheral tissue which had been included with the body when dissections were based on gross appearance and how much this might influence analysis of the composition. This local variation emphasises the need for careful anatomical description in studies of the composition of menisci, but suggests that previously noted changes in the composition of menisci in osteoarthritis result from the disease, not dissection differences.