This histological study is based on a macroscopical study of post-mortem hip joints (Byers, Contepomi, and Farkas, 1970) in which two categories of articular cartilage alterations, in addition to osteophytes, were described. One category consisted of 'limited' alterations which occurred frequently, had several subcategories, and rarely led to joint deformity. The other consisted of progressive alterations which caused bone exposure and joint deformity. Histological sections from both groups, including all the subcategories of the first, were studied. Initially the mechanisms that destroy cartilage were determined, and then their prevalence was assessed. Six mechanisms were found, all occurring in the group of limited alterations with varying prevalence and in varying combinations. Only one, fibrillation, occurred in the progressive group.