Articular chondrocytes from eight mammalian species (rabbit, opossum, woodchuck, cat, dog, sheep, rhesus and cebus monkeys) were grown in monolayer culture using a single regimen. The animals were immature or young adults. Ham's F12 medium supplemented with 10% fetal bovine serum was employed for the primary cultures and Dulbecco-Vogt medium, for the secondary. Marked species differences were found with respect to cell morphology, growth in primary and secondary cultures, incorporation of radiosulfate into macromolecules, adhesion to the flask surface, response to vitamin C, and chondroid expression in spinner bottles. Under these particular conditions, rabbit chondrocytes grew most rapidly and incorporated several times more sulfate than did the others. Additional experiments carried out with other media on four of the species indicate that optimal conditions for culturing mammalian chondrocytes must be determined for each species individually.