The aim of the current study was to compare total paracentesis associated with dextran-40 infusion with diuretics in the treatment of tense ascites in patients with cirrhosis. Eighty patients were randomly allocated to two groups: 40 patients were treated with paracentesis plus dextran-40 infusion (8 g per liter of ascitic fluid removed), and 40 patients with diuretics. After treatment patients were discharged with diuretics, and patients developing tense ascites during follow up (54 +/- 4 weeks) were treated according to their initial schedule. Paracentesis was more effective than diuretics in mobilizing the ascitic fluid. The incidence of complications was significantly higher (p < 0.05) in the diuretic group (38%) than in the paracentesis group (15%). This difference was mainly due to a higher incidence of hepatic encephalopathy in the former group (30% vs. 2.5%). A significantly higher incidence of hepatic encephalopathy was also observed in the diuretic group during the follow-up readmissions for ascites recurrence. There were no significant differences between the two treatment groups in the probability of survival after inclusion. Plasma renin activity and plasma aldosterone concentration measured before and 2 and 6 days after paracentesis in 20 randomly selected patients increased significantly (p < 0.05) (baseline values: 5.3 +/- 1.4 ng.ml-1.h-1 and 63 +/- 21 ng/dl; 48 h after paracentesis: 11.7 +/- 3.9 ng.ml-1.h-1 and 99 +/- 31 ng/dl; 6 days after paracentesis: 10.9 +/- 3 ng.ml-1.h-1 and 110 +/- 27 ng/dl).(ABSTRACT TRUNCATED AT 250 WORDS)