Portal hypertension is a major risk factor for hepatic failure or intestinal bleeding in patients with liver disease but cannot be measured indirectly. We attempted to comprehensively evaluate preoperative parameters of functional liver reserve that correlated with portal pressure (PP) in patients with various liver diseases. We examined 93 patients in whom portal pressure was directly measured during preoperative portal vein embolization (PVE) or operation. Background liver included chronic viral liver disease in 43 patients, obstructive jaundice in 29 patients, and normal liver in 21. Multivariate logistic analysis and linear regression analysis were applied to create a predictive formula for PP. Mean PP was 13.4±4.9 cm H 2 O, and PP was significantly associated with severity of liver injury, hepatic fibrosis, intraoperative blood loss, and post-hepatectomy morbidity (p<0.05 each). Mean PP after PVE (22.5±7.8 cm H 2 O) was significantly increased compared to that before embolization (13.1 ± 4.7 cm H 2 O; p<0.01). Univariate analysis identified seven significant parameters of preoperative liver function associated with PP: indocyanine green (ICG) test result, liver uptake and clearance index (HH15) on 99m Tc-galactosyl serum albumin liver scintigraphy, total bilirubin level, prothrombin activity, and hyaluronate level. Using multiple linear regression analysis, the predictive formula using ICG and HH15 was as follows: Y (estimated PP)=0.273+0.086×ICGR15+ 0.193×HH15. The calculated PP (11.5±4.6 cm H 2 O (−1.9 cm H 2 O)) was lower than true PP, which was significantly associated with post-hepatectomy morbidity (p<0.05). The correlation between true and calculated PP was weak, and prediction using the conventional liver functional parameters was limited at present and, however, estimating PP appears to be useful in evaluating portal hypertension and post-hepatectomy morbidity.