Acute leukemia are now in progress with intensive and prolonged polychimiotherapy but such medicine is difficult to manage because veins are rapidly unserviceable. In order to simplify hematological treatment and psychological approach of this patients we have constructed arterio-venous fistula in children with malignancy. The operation of choice is a subcutaneous cephalic-vein to-radial-artery arterio-venous fistula on the fore arm at the distal part. 103 of this vascular access procedures are performed in 93 children and in infants weighing less than 10 kg: 57 are performed without magnification, 46 with the aid of operative microscope. The comparative study of this two procedures show that microsurgical technique is necessary to improve results, especially in the youngest patients. This vascular access are well accepted by the children and his families, and very useful for the medical staff.