Total paracentesis is widely used in the treatment of patients with cirrhosis and tense ascites. However, very little information is available regarding its consequences on splanchnic circulation, and its effects on portocollateral blood flow have not been investigated. Ten cirrhotic patients admitted because of tense ascites had measurements of hepatic and systemic hemodynamics, renal function and endogenous vasoactive neurohumoral systems at baseline, just after total paracentesis and 1 hr later. Total paracentesis caused a significant increase in cardiac output (+11%; 95% confidence interval, +4% to +19%) and a rapid fall in portal pressure, as shown by significant decreases in both the wedged hepatic venous pressure (-27% +/- 8%; p < 0.005) and the hepatic venous pressure gradient (-10%; 95% confidence interval, -3% to -18%). This was accompanied by a marked decrease in azygos blood flow (-28%; 95% confidence interval, -13% to -43%). These favorable hemodynamic effects were associated with a fall of the elevated levels of plasma renin activity (-47% +/- 9%; p < 0.05), plasma aldosterone (-31% +/- 21%; p < 0.05) and plasma norepinephrine and by a decrease in levels of serum creatinine (-24% +/- 15%; p < 0.05) and blood urea nitrogen (-4% +/- 3%; p < 0.05). These changes were maintained 1 hr later. This study indicates that in patients with cirrhosis and tense ascites total paracentesis favorably influences the systemic hemodynamics, portocollateral blood flow and portal pressure.