1. The entity termed acute necrosis of cartilage has again been described
2. The literature concerning this disease has been reviewed and the recent emphasis on the race of the patient has been noted.
3. Two cases of acute necrosis of cartilage in slipping of the capital femoral epiphysis have been presented with roentgenograms, gross findings, and microscopic sections.
4. Based on these findings, it is concluded that race may play some part but that the disease can occur in any racial group and that infection, deprivation of blood supply to the femoral head, and rheumatoid arthritis were not etiological agents in the two patients studied. It was postulated that the cartilage perished as a result of interference with the production of synovial fluid, but no explanation was found as to why this should occur following slipping of a capital femoral epiphysis.