BACKGROUND Systemic hypertension is one of the main risk factors for atherothrombosis. Tissue factor (TF) is found in the adventitia of blood vessels and in the lipid core of atherosclerotic plaques, and is specifically expressed on monocyte or macrophage cell membrane surfaces. TF plays a pivotal role in blood clotting physiology and is involved in pro-inflammatory action and atherosclerotic plaque destabilization. OBJECTIVE In this study we investigated whether there is any relationship between TF messenger RNA expression and activity in blood monocytes isolated from hypertensive patients with clinical signs of atherosclerosis, uncomplicated hypertensive individuals and normotensive control subjects. METHODS Eighty subjects (41 men and 39 women, mean age 41 +/- 12 years) with untreated essential hypertension and 41 control subjects matched for sex and age were enrolled in the study. Patients were classified according to whether they had a normal (</= 1 mm, 41 patients) or abnormal (> 1 mm, 39 patients) intima-media thickness (IMT). RESULTS TF mRNA expression and activity in hypertensive individuals with no carotid atherosclerosis were no different from control subjects in unstimulated and stimulated monocytes. Abnormal IMT patients showed a higher TF mRNA expression compared with normal IMT hypertensive subjects (P < 0.001). CONCLUSIONS We demonstrated that TF mRNA and activity levels in monocytes obtained from uncomplicated hypertensive individuals are comparable with those of normotensive subjects, whereas atherosclerotic hypertensive patients showed increased levels of these parameters.