Vascular endothelial growth factor (VEGF) plays an important role in the regulation of tumour growth and metastasis. It was the aim of this study to examine the impact of serum VEGF levels on the likelihood of response to radiotherapy and on the disease-free survival in patients with cervical cancer. Blood was taken before commencing treatment and serum VEGF was assessed by quantitative ELISA in 23 patients with cervical cancer stage IB-IVA undergoing primary radiotherapy. Serum VEGF levels were correlated with clinical and histopathologic factors as well as with response to radiotherapy and time to progression. Nineteen of the 23 patients had a complete response and four patients had persistent disease at 3 months. The median follow-up was 25 months (95% confidence interval: 23.5-26.5 months). At the time of analysis, eight patients were tumour-free and 15 patients had tumour progression; 12 of these 15 patients died of disease. Overall, the median serum VEGF level was 244 pg/ml (range 31.9-817.6 pg/ml). All four patients with local failure had VEGF levels >244 pg/ml, whereas 11 of the 19 patients with complete response had serum VEGF of < or =244 pg/ml (P=0.035). The median time to progression was 5 months in patients with VEGF of >244 pg/ml compared to 19 months in patients with VEGF of < or = 244 pg/ml (log rank, P=0.003). In multivariate analysis, serum VEGF, tumour size and histological type, but not the patient's age, stage and grade of histological differentiation influenced the progression-free survival. Elevated pre-therapeutic serum VEGF levels are associated with poor response and a shorter time to progression in patients with cervical cancer undergoing primary radiotherapy.