Some cirrhotic patients have hepatic veno-venous communications (HVVC) and large porto-systemic collaterals. However, the relationship between wedged hepatic vein pressure (WHVP) and portal vein pressure (PVP) in such patients is not clear. The aim of this study was to determine the relationships between simultaneously measured WHVP and PVP, and occluded hepatic and splenic portal venography in 100 cirrhotic patients (40 alcoholic and 60 hepatitis C virus (HCV)-related cirrhosis). PVP and WHVP were closely related in both groups (alcoholic-cirrhosis: 27.8 +/- 4.7 and 27.5 +/- 4.8 mmHg, HCV-cirrhosis: 27.3 +/- 3.7 and 26.2 +/- 4.4 mmHg, respectively). Occluded hepatic venography revealed that 13 of the 100 patients had HVVC (alcoholic-cirrhosis: 4, HCV-cirrhosis: 9). In patients with HVVC, PVP (27.9 +/- 3.0 mmHg) was significantly higher than WHVP (21.9 +/- 3.3 mmHg, P < 0.001). Large porto-systemic collaterals did not affect the relationship. We conclude that HVVC affects the relationship between PVP and WHVP. When WHVP is measured, occluded hepatic venography should be examined to detect HVVC.