BACKGROUND/AIMS: To determine dynamics of albumin in plasma and ascitic fluid of patients with cirrhosis. METHODS: Forty-seven patients were classified in four groups: I--patients without fluid retention; II--patients with ascites not resistant to subsequent diuretic treatment; III--recompensated patients during diuretic treatment; and IV--patients with diuretic-resistant ascites. Transvascular and transperitoneal albumin transports were quantified by 131I-/125I-labelled human albumin. RESULTS: TER(P) (i.e. the fraction of intravascular albumin (IVM) passing from plasma into the interstitial space per hour) was increased in all groups. In group IV patients the transport rate of albumin from plasma into the ascitic fluid (TER(PA)) was significantly higher than the transport rate from the ascitic fluid back into the plasma: TER(AP) (0.45 vs. 0.26% IVM/h, P < 0.002). In group II patients TER(PA) was similar to TER(AP) (0.27 vs. 0.25% IVM/h, ns). A direct correlation was found between TER(PA) and TER(AP) in both groups of patients (r = 0.78, P < 0.001). CONCLUSION: In non-resistant ascites, there is a steady state between the transport of albumin into the peritoneal cavity and back into the plasma, but in resistant ascites the former transport is elevated. Thus, local factors may be important to treatment of ascites.