Allograft renal thrombosis can occur in 1 to 6% of cases. Many predisposing factors has been identified especially alteration of coagulation. We analyzed in this retrospective study frequency and predisposing factors of renal graft thrombosis. Among 319 renal transplant recipients, 9 patients (2,8%) presented veinous graft thrombosis in 5 cases and arterial thombosis in 4 cases. There were 6 men and 3 women aged of 30,6 years meanly (10-56) which developed the thrombosis 6 days (1-48) after the ransplantation. Surgical difficulies were noted in 3 cases and all patients didn't received preventive anticoagulation. Detransplanted was performed in all cases after 16,2 days and 1 patient died. Thrombosis constitutes an important cause of graft loss. A perfect surgical technic and prophylactic treatment in high risk patients are necessary toreduce this complication.