The aim of this study was to determine in what way HHT (hereditary hemorrhagic telangiectasia) patients with mutations for the endoglin (ENG) or activin receptor-like kinase 1 (ACVRL1) gene show different expression levels of the angiogenic factor VEGF (vascular endothelial growth factor) by correlating VEGF to the HHT genotype. In 18 HHT patients, who were screened for ENG and ACVRL1 gene mutations and 25 healthy controls the VEGF plasma level as well as the VEGF tissue expression were determined by ELISA technique and cryostat sections of the nasal mucosa. In general, the VEGF plasma levels as well as the VEGF tissue expression were significantly higher in HHT patients compared to healthy controls. However, the correlation of VEGF to the HHT genotype did not show any significant differences, ie the VEGF plasma levels as well as the VEGF tissue expression in HHT patients with ENG gene mutations did not differ significantly to those of HHT patients with ACVRL1 gene mutations or mutations for both the genes. In spite of the fact that the angiogenic factor VEGF seems to play an important role in the pathogenesis of HHT, it cannot serve as a specific diagnostic screening marker. These results underline the importance and necessity of molecular analyses in HHT patients.