Vascular endothelial growth factor (VEGF) is an important mediator of vascular development in tumors. We aimed at clarifying the relationship between VEGF mRNA expression and invasion or metastasis of hepatocellular carcinoma (HCC). Reverse transcript-polymerase chain reaction (RT-PCR) was carried out on surgical specimens of 48 patients with HCC. The relative levels of VEGF mRNA expression were measured by determining a ratio between PCR products of VEGF and the endogenous internal standard gene beta-actin. Expression of VEGF mRNA in tumor was found in 76.5% (39/51) of patients, whereas it was 21.69% (11/51) in non tumorous liver. The levels of VEGF mRNA expression in tumors with tumorous emboli and in poor-encapsulated tumors were higher than that without tumorous emboli and in well-encapsulated tumors respectively (p < 0.05 t test). There was no significance in the expression of VEGF mRNA between large HCC (diameter > 5cm) and small HCC (diameter < or = 5cm) (p > 0.05). VEGF may play an important role in the invasion and metastasis of HCC. Angiogenesis in tumor correlates with progression of HCC.