AIM: To investigate the expression level of plasma vascular endothelial growth factor (P-VEGF) in patients with hepatocellular carcinoma (HCC) and its relationship with the clinicopathologic characteristics, and to examine the changes of P-VEGF in the course of transcatheter arterial chemoembolization (TACE).METHODS: Peripheral blood samples were taken from 45HCC patients before and 1, 3, 7 d, and 1 mo after TACE.Plasma VEGF level was measured with the quantitative sandwich enzyme-linked immunosorbent assay (ELISA).Twenty patients with benign liver lesions and 17 healthy control subjects were also included in this study.RESULTS: Plasma VEGF levels in HCC patients were significantly elevated as compared to those in patients with benign liver lesions (P = 0.006) and in the normal controls(P = 0.003). Significant differences were observed when P-VEGF was categorized by tumor size (P = 0.006), portal vein thrombosis (P= 0.011), distant metastasis (P= 0.017),arterial-portal vein shunting (P = 0.026), and Intational Union Against Cancer (UICC) TNM stage (P = 0.044). There was no correlation between plasma level of VEGF and the level of alpha fetoprotein (α-FP) (r = 0.068, P = 0.658) and weakly correlated with the number of platelets (r = 0.312,P = 0.038). P-VEGF levels increased significantly and reached the peak value on the first day after TACE, and then decreased gradually. The change rate of P-VEGF concentration(one month post-TACE/pre-TACE×100%) was correlated with the retention rate of lipiodol oil (rs = 0.494, P = 0.001)and the tumor volume change (rs = 0.340, P = 0.034).The patients who achieved a partial or complete response to TACE therapy showed significantly less pre-treatment P-VEGF than those nonresponders (P = 0.025). A high pretherapeutic P-VEGF level was associated with poor response to treatment (P = 0.018).CONCLUSION: A high pre-treatment P-VEGF level is a useful marker for tumor progression, especially for vascular invasion. TACE increases the level of P-VEGF only temporarily which may be associated with tumor ischemia.P-VEGF may be useful in predicting treatment response,monitoring disease course after TACE and judging the effect of different TACE regimens.