['Urotensin II is the most potent vasoconstrictor known. Its role in hypertension has not been investigated. Here, we studied the plasma levels in hypertensive and normotensive human subjects.', 'A cross-sectional case-control study.', 'Hypertension clinic and research clinic of a university teaching hospital.', 'Sixty-two hypertensive outpatient subjects (52% male, aged 57 +/- 13 years) and 62 normotensive controls (45% male, aged 54 +/- 13 years) recruited from the general population.', 'Plasma urotensin II levels measured by radioimmunoassay, systolic and diastolic blood pressure.', 'Plasma urotensin II was 8.8 +/- 0.9 pmol/l in normotensive controls and 13.6 +/- 1.4 pmol/l in hypertensive subjects (P = 0.005). In multiple regression analysis, systolic blood pressure was related to plasma urotensin II (beta = 0.31, P < 0.001) and age (beta = 0.28, P = 0.001), accounting for 10 and 8%, respectively, of the variance in systolic blood pressure. There was no significant correlation with gender, renal function or diabetes.'] Is plasma concentration of urotensin II raised in hypertension?