Hypertension is a frequent finding in uremic patients. The pathogenesis of this complication in uremia is complex and not fully elucidated. An imbalance between the vasoconstrictor and vasodilator systems may be involved in its pathogenesis. In this study we have evaluated the state of nitric oxide (NO) and adrenomedullin (ADM) in hemodialyzed patients, especially those with hypertension. We included a group of hypertensive hemodialyzed patients (n = 9) and a group of normotensive control patients (n = 10). We measured plasma renin activity, as well as plasma catecholamines, ADM, and nitrite/nitrate levels in basal conditions before starting the hemodialysis session. Plasma volume, as well as left ventricular ejection fraction were also measured. Hemodialysis patients showed plasma levels of nitrite/nitrates and ADM higher than the reference values in the normal population. We observed no differences in the plasma levels of nitrite/nitrates, but ADM levels were higher in hypertensive (278.2 +/- 15.5 pg/ml) patients than in normotensive patients (225 +/- 9.9 pg/ml) (p < 0.05). When considering all patients together, mean arterial pressure positively correlated with plasma ADM (r = 0.468, p < 0.05). Plasma volume and left ventricular ejection fraction were similar in the two groups of patients. In summary, plasma levels of nitrite/nitrates and ADM are increased in hemodialyzed patients, although only ADM levels were further increased in hypertensive patients. Our results do not suggest that a decreased production in the vasodilator factors evaluated is involved in the pathogenesis of hypertension in uremic patients.