The effects of zinc and copper ions on the structure, proliferative capacity and proteoglycan metabolism of lapine articular chondrocytes were studied in a monolayer culture system. Zn++ was cytotoxic at a concentration of 100µmol/l, whereas 50 µmol/l caused a stimulation of chondrocyte proliferation with simultaneous reduction (p& < 0.01) in macro-molecular binding of 35SO4. 10 µmol/l Zn++ failed to evoke any alteration in these parameters. Cu++ concentrations of 100 and 50 µmol/l significantly reduced cell proliferation (p& < 0.01) with a concomitant stimulation of 35SO4 uptake into pro teogly cans. 10 µmol/l Cu++ did not significantly alter chondrocyte multiplication nor binding of 35SO4 It is proposed that Zn++ may play a role in chondrocyte damage in joint disease. Furthermore, the possible therapeutic efficacy of copper in maintaining cartilage integrity is supported.