Abstract—A_2A adenosine receptors inhibit neutrophil adhesion and superoxide anion generation. The aim of the present study was to evaluate the effect of antihypertensive treatment with doxazosin or propranolol on the binding and functional parameters of A_2A adenosine receptors of lymphocytes and neutrophils in essential hypertensive patients. Two groups of previously untreated, essential hypertensive patients were studied. The mean affinity (K_d) and density (B_max) of adenosine receptors, by the A_2A selective radioligand [³H]-ZM-241385 binding assays, and EC₅₀, by cAMP assays, were obtained first on no medication and a second time after treatment for up to 13 weeks with doxazosin (13 patients) or propranolol (8 patients). A third group of 15 healthy normotensive volunteers matched by age, sex, and body mass index was used as a control. Binding and functional parameters of the A_2A adenosine receptors were significantly higher in the 2 hypertensive groups than in controls (P always <0.0001), both in lymphocyte and neutrophil membranes. After treatment with propranolol, the binding parameters did not change significantly, whereas after treatment with doxazosin, K_d, B_max, and EC₅₀ values returned to control levels. In never-treated essential hypertensive patients, lower affinity, higher density, and impaired function of A_2A adenosine receptors are present. The binding and functional parameters of A_2A adenosine receptors appear to be normalized after treatment with doxazosin but not with propranolol.