In this study the predictivity of captopril test was investigated in 17 HD and 12 CAPD patients, all oj whom were hypertensive. The patients had ultrafiltration until dizziness, muscle cramps appeared. Only those patients remained hypertensive after ultrafiltration were given enalapril. Captopril test predictability were 88% in hypervolemic subgroup, and 78% in normovolemic patients. Pre/post-UF cardiothorasic index; left atrium and other echocardiographic parameters; captopril test positivity were compared. HD group (8.9+3.7%; 5.5+2.9%) and normovolemic/hypervolemic HD subgroups (6.6±2.3;3.3±2.6)/(9.6±3.4; 6.7+2.7) needed more ultrafiltration compared to CAPD patients (p<0.05). HD patients had higher cardiothorasic index than those of CAPD both before (0.54+0.05; 0.47+0.06, p<0.05) and after (0.45+0.04, 0.41+0.05; p<0.05) ultrafiltration. Regarding left atrium, the difference (27.6+4.6; 19.3+3.3, p<0.001 before UF; 21.1+2.4; 15.5+2, p<0.001 after UF) was also maintained. As a result, in all hypertensive patients regardless of the volume status, ultrafiltration must be the first treatment step, if proves ineffective, an ACE inhibitor must be given.