Blood volume, extracellular volume, blood pressure and the plasma levels of angiotensin II, aldosterone, adrenaline, noradrenaline and arginine vasopressin were determined in sixteen normotensive (group 1) and thirteen hypertensive patients (group 2) with chronic glomerulonephritis and in eleven normotensive control subjects (group 3). Blood volume and extracellular volume did not differ between the groups and no significant differences were found in any of the hormones measured when comparing group 1 or group 2 with group 3. In the hypertensives but not in the normotensives or control subjects, a highly significant positive correlation was found between diastolic blood pressure and blood volume (rho = 0.75, P less than 0.01) and between diastolic blood pressure and extracellular volume (rho = 0.74, P less than 0.01). Blood volume and extracellular volume correlated (P less than 0.05) in each of the groups. In conclusion, although no expansion of either blood or extracellular volume was found in chronic glomerulonephritis, a positive volume-pressure relationship could be demonstrated in hypertensive patients suggesting a role of volume factors in the pathogenesis in early stage chronic glomerulonephritis. The study does not give support to a major role of either angiotensin II, arginine vasopressin or catecholamines in the maintenance of nonmalignant hypertension in early stage chronic glomerulonephritis.