Cardio-vascular abnormalities appear very often in end-stage renal failure patients. Because of this we have examined 54 patients, children and adolescents, 35 patients underwent haemodialysis (HD) and 19 continuous ambulatory peritoneal dialysis (CAPD). We can observe that the anatomical status of the heart was dependent upon the time of the treatment. The function of the heart was normal much longer. Structural heart's abnormalities were observed earlier in patients on HD than on CAPD.