We evaluated a group of 21 cirrhotic patients with a standard 20 ml/kg water load. The patients segregated into three classes: class I (n = 6) had normal water load excretion, i.e. greater than 80% excretion over 5 h (mean 82.3 +/- 0.8%); class II (n = 8) had 20-80% excretion (mean 38.6 +/- 4.2%); and class III (n = 7) had less than 20% excretion (mean 12.9 +/- 1.2%). The patients in class III, who had profound impairment of water load excretion, were found to have a higher frequency of tense ascites, lower serum sodium concentrations, diuretic resistance, impairment of urinary sodium excretion, lower inulin and p-aminohippurate clearances, and elevations of plasma arginine vasopressin, aldosterone and norepinephrine concentrations. However, class III could only be distinguished from class II on the basis of excretion of a standard water load. No significant differences were found among the classes in liver function tests. We prospectively followed these patients. Classes I and II patients appear to have a good prognosis, if they avoid ethanol (4 of 5 patients still alive 42-56 months after evaluation). Class III patients have a poor prognosis independent of ethanol intake (all lived less than 5 months, except 1 patients who received a peritoneovenous shunt). Class I patients were found to tolerate continued ethanol consumption better than class II patients. Thus, an early intervention, such as the peritoneovenous shunt, may prolong survival among class III patients; however, this possibility needs to be evaluated in a larger prospective study.