OBJECTIVES:　To　investigate　cell　morphology,　aggrecan　expression,　and　type　I,　II,　III　and　X　collagen　expression　in　chondrocytes　from　adults　with　Kashin-Beck　disease　or　osteoarthritis　(OA).　METHODS:　Samples　of　knee　articular　cartilage　were　taken　during　surgery;　cartilage　samples　obtained　from　fresh　cadavers　without　arthritic　disease　were　used　as　controls.　Samples　were　digested　with　collagenase;　isolated　chondrocytes　were　cultured　in　monolayers.　Aggrecan　was　detected　by　toluidine　blue　staining;　collagen　and　aggrecan　protein　levels　were　evaluated　by　immunocytochemistry　and　immunofluorescence　staining.　RESULTS:　Samples　were　obtained　from　six　participants　per　group.　Aggrecan　and　type　II　collagen　levels　in　chondrocytes　from　patients　were　significantly　lower　than　those　from　controls,　but　levels　of　type　I,　III　and　X　collagen　were　enhanced　in　patients　compared　with　controls.　Production　of　type　III　and　X　collagen　was　higher　in　chondrocytes　from　patients　with　Kashin-Beck　disease　than　in　those　from　OA　patients.　CONCLUSIONS:　Biochemical　and　morphological　mechanisms　underlying　Kashin-Beck　disease　and　OA　include　enhanced　dedifferentiation　and　hypertrophy　of　chondrocytes,　increased　type　I,　III　and　X　collagen　levels,　and　suppressed　type　II　collagen　and　aggrecan　production　compared　with　control　samples.