Over a period of observation of 14 years, one or more aspetic osteonecroses (AON) were discovered in 29 patients who had undergone renal transplantation. Altogether 64 AON were discovered. In patients who had survived at least 1 year, the frequency of this lesion was 18 percent. These transplantation necroses were often bilateral (16 cases out of 21 AON of the femoral head) or multiple (6 patients presenting AON in more than 3 sites) ; necroses were sometimes found in unusual sites (shoulder, ankle, upper end of the tibia, scaphoid, condyle of the humerus). The AONs of the lower limbs were remarkable because of their extent and because of the rapid evolution of the radiological signs. This is in contrast to the moderate nature of the pain. Latent types of necrosis are also found (3 cases of AON of the femoral head). During a search for factors favouring the development of AON, the authors noted that the average duration of haemodialysis was longer in the patients with AON than in a control group of transplant patients. The average daily dose of corticoids for the first six months after transplantation was not significantly different in the two groups studied. However, the 15 patients with transplants who were not given corticoids did not develop AON.