The avascular osteonecrosis (AVN) is a serious osseous complication after renal transplantation. Its prevalence clearly decreased from 20 to 4 % after introduction of the cyclosporine and the reduction of the steroid doses. The aim of our study is to evaluate the frequency of the AVN among our kidney transplant recipients and to determine the risk factors by comparing them with a population without AVN. Among the 326 kidney transplant recipients between June 1986 and December 2004, fifteen patients developed an AVN (group I) with mean age: 40.86 years, they were 11 men and 4 women. Fifteen kidney transplant recipients without AVN matched for age, gender and date of transplantation were selected (group II). Cases of symptomatic AVN were diagnosed by hip radiographs, radioisotope bone scan or magnetic resonance imaging. The AVN was diagnosed 3 years after transplantation (range: 6 months – 13 years). The main localisation of the AVN is the fem head in 12 cases and the fem condyle in 3 cases. We studied the following risk factors: The type of donor (cadaveric or living donor), the time between beginning of dialysis and transplantation, the cumulative steroid dose, the number of acute rejection episodes, and the post transplantation weight gain. The statistical analysis showed that the acute rejection episodes were higher in group I than group II (p=0.05) and the cumulative steroid dose was higher in group I (p=0.04). The prevalence of the AVN in our population is 4.6%; it is probably underestimated since they are symptomatic cases. The reduction or early withdrawal of steroids remains the only efficient preventive treatment.