['To investigate the role of chondrocyte apoptosis in the initiation and severity of articular cartilage (AC) damage.', "Articular cartilage from equine metacarpophalangeal (MCP) (n = 13) and metatarsophalangeal (MTP) (n = 16) joints was used and each graded macroscopically for cartilage degradation (macroscopic osteoarthritis [OA] grade). Cartilage was sampled from six regions on the articular surface of both joint types and graded using a 'modified' Mankin scoring system. Apoptosis of chondrocytes in cartilage sections was assessed by expression of active caspase-3 using indirect immunohistochemistry.", "\u2002 Apoptosis was found to increase significantly with macroscopic OA grade (P < 0.0001). There was a significant trend for increasing 'modified' Mankin score with increasing macroscopic OA grade (P < 0.0009). Apoptosis was significantly higher in the superficial zone than in the middle or deep zones (P < 0.01 and P < 0.001, respectively). The incidence of apoptosis correlated significantly with the early stages of microscopic cartilage damage ('modified' Mankin scores 0-3). Significant differences in overall apoptosis were noted when cartilage specimens with a 'modified' Mankin score of 3 were compared to grade 2 (P < 0.001), grade 1 (P < 0.001) and grade 0 (P < 0.05) specimens. However, no significant difference in overall apoptosis was noted between grade 3, 4 and 5 samples."] Is chondrocyte death by apoptosis associated with the initiation and severity of articular cartilage degradation?