Catecholamines due to various mechanisms may contribute to the accumulation of collagen fibers and extracellular matrix in the arterial wall. The aim of this study was to compare intima-media thickness (IMT) of the common carotid artery (CCA) and carotid bifurcation (CB) in patients with pheochromocytoma, essential hypertension and healthy controls. Carotid ultrasound studies were carried out in 30 patients with pheochromocytoma matched for age and gender with 80 patients with essential hypertension and 40 normotensive controls. Significantly higher IMT was found in patients with pheochromocytoma and essential hypertension compared to controls when measured in the CCA (0.931+/-0.223, 0.825+/-0.146 and 0.738+/-0.113 mm; P<0.001; P<0.05), and only in patients with pheochromocytoma compared to controls in the region of CB (1.359+/-0.593, 1.095+/-0.311 and 0.968+/-0.247 mm; P<0.001; P=0.13). Higher IMT in patients with pheochromocytoma compared to patients with essential hypertension was also statistically significant in both carotid regions (both P<0.01). This difference remained significant after adjustment for all relevant clinical and biochemical covariates in the CCA (P=0.014) but disappeared in the region of CB (P=0.079). In summary, patients with pheochromocytoma have increased common carotid IMT when compared to patients with essential hypertension. This finding could be caused by the deleterious effects of the excess of catecholamines on the vascular wall growth and thickening.