Abstract: Objective To investigate chondrocyte apoptosis and the expressions of Bcl-2, Bax, Fas and iNOS in the articular cartilage between Kashin-Beck disease (KBD) and primary osteoarthritis (OA) and explore the difference in pathogenesis between the two diseases. Methods The articular cartilage specimens were collected from 15 normal human subjects, 15 adult patients with KBD and 15 with OA. Chondrocyte apoptosis was detected by TUNEL method, and the expressions of Bcl-2, Bax, Fas and iNOS in articular cartilage were examined with B-SA immunohistochemistry. Results The percentages of apoptotic chondrocytes positive for TUNEL staining in the articular cartilage were significantly higher in patients with KBD and OA than in normal control subjects (F=20.90-53.16, df=42, P<0.01), and the erosive areas of the articular cartilage contained greater percentage of apoptotic chondrocytes than the non-erosive areas in the same patient with KBD (t=4.154, df=28, P<0.01) or OA (t=6.004, df=28, P<0.01). No significant difference was noted in the positive apoptotic chondrocytes between KBD and OA (t=1.329-1.362, df=28, P>0.05). The percentage of chondrocytes positive for Bcl-2, Bax, Fas and iNOS were significantly higher in KBD and OA patients than in the control subjects (F=25.46-215.31, df=42, P<0.01), and significant differences were observed in Bcl-2, Bax, Fas and iNOS expressions between the erosed areas and non-erosed areas in articular cartilage in patients with KBD (t=2.608-7.77, df=28, P<0.05) and OA (t=2.278-5.413, df=28, P<0.05), but their expressions showed no significant difference between the two diseases (t=0.284-1.590, df=28, P>0.05). Conclusion There was no significant difference in apoptotic chondrocytes and Bcl-2, Bax, Fas and iNOS expressions in the cartilage between adult patients with KBD and OA.