To investigate whether albumin can be substituted by less expensive plasma expanders in cirrhotic patients with tense ascites treated with total paracentesis, 88 patients (16 with renal failure) submitted to this therapeutic procedure were randomly assigned to receive IV albumin (43 patients) or dextran-70. Both substances were given at a dose of 8 g/L of ascitic fluid removed. Patients were discharged from the hospital with diuretics, and cases developing tense ascites during follow-up were treated according to their initial schedule. Total paracentesis was effective in eliminating the ascites in all but two cases in each group. Neither paracentesis plus IV albumin infusion nor paracentesis plus IV dextran-70 infusion was associated with significant changes in renal and hepatic function or serum electrolytes. The incidence of renal impairment (one case in each group), hyponatremia (three and four cases, respectively), and other complications (hepatic encephalopathy, gastrointestinal hemorrhage, bacterial infections) after paracentesis, and the clinical course of the disease as estimated by the probability of readmission to hospital during follow-up, causes of readmission, probability of survival, and causes of death were similar in the two groups of patients. The effect of paracentesis on effective intravascular volume was indirectly assessed by measuring plasma renin activity and aldosterone concentration before and 2 and 6 days after treatment, the patients being without diuretics. In patients treated with albumin, no significant changes in renin and aldosterone were observed during the entire period of observation. In contrast, both parameters increased significantly on the 6th day of treatment in patients receiving dextran-70. A significant increase in plasma renin activity and aldosterone concentration (30% over baseline values) was observed in 51% of patients treated with dextran-70 and in only 15% of those treated with albumin (x2 = 10.4; P = 0.0012). These results indicate that although dextran-70 is less efficacious than albumin in protecting cirrhotic patients treated with total paracentesis from the decrease in effective intravascular volume, it appears to be capable of preventing the renal and electrolyte complications induced by this therapeutic procedure.