Vascular endothelial growth factor (VEGF) is a specific mitogen for endothelial cells and an inducer of the angiogenic procedure. Endothelial nitric oxide (NO) is a potent vasodilator. Because both are implicated in vascular function, it is possible that they would be significantly affected in arterial hypertension. The aim of the study was the investigation of the levels of the two substances in blood serum and their potential relation in patients with untreated essential arterial hypertension compared to healthy individuals. VEGF levels were found 129.1 +/- 135.9 pg/mL in a group of 28 untreated hypertensive patients vs. 209.0 +/- 133.3 pg/mL in a group of 28 healthy individuals (p = 0.008). Nitrites and nitrates levels (as an indirect index of calculating NO levels) were also lower in hypertensive patients than in healthy individuals (19.8 +/- 9.7 micromol/L vs. 29.6 +/- 15.9 micromol/L, p = 0.014). A positive correlation between NOx (nitrites and nitrates levels) and VEGF was found in healthy individuals (r = 0.55, p = 0.003), but there was no correlation in hypertensive patients. The significant decrease of serum VEGF and NO in arterial hypertension and the existence of a correlation between the two substances in healthy subjects that did not exist in the hypertensive patients are findings that need evaluation.