Inorganic phosphate (Pi) induces DNA fragmentation in chondrocytes. Chondrocytes were cultured for 24 hours in the presence of 10% NUSERUM (NU), in serum-free media (SF), and in serum-free media supplemented with 5 mM Pi. At the end of the cultured period, cells were lysed, and then histone-complexed DNA fragments were detected with a colorimetric ELISA assay. *Significantly different from NU and SF (P < .05)