Angiogenesis is a crucial step in tumour growth, progression, and metastasis. Recently, many angiogenic factors have been identified. Vascular endothelial growth factor (VEGF) is thought to be one such angiogenic factor and is also thought to be a selective mitogen for vascular endothelial cells. The present study was designed to determine the circulating levels of VEGF in human oral squamous cell carcinoma (OSCC) and to investigate its correlation with the clinicopathologic features and prognosis. The study consisted of 10 healthy volunteers and 31 patients with OSCC. A quantitative sandwich enzyme immunoassay technique was used to measure the concentrations of VEGF in the sera. The data obtained from the experiment were analysed with independent-samples t-test. The mean concentrations of serum VEGF were 148.80 +/- 64.17 pg x ml(-1) (range, 59-231 pg x ml(-1)) in normal controls and 567.97 +/- 338.17 pg x ml(-1) (range, 136-1,892 pg x ml(-1)) in OSCC group. Statistical analysis showed that the mean VEGF level in sera of OSCC patients was significantly higher than that in healthy controls (P<0.001). The serum VEGF levels of OSCC patients correlated with condition of nodal metastasis (P<0.05) and clinical stage (P<0.05) but not with sex (P>0.05) and degree of differentiation (P>0.05). Our study showed that OSCC was associated with significantly elevated serum VEGF concentration. Higher level of serum VEGF also correlated with lymph node metastasis and clinical stage of OSCC. Determination of serum VEGF concentration may be helpful to distinguish OSCC patients from the normal individuals.