This study was designed to assess a possible correlation between flow-mediated endothelium-dependent vasodilation in the popliteal artery and the intima-media thickness of the common carotid artery. Impaired vasodilation is one of early markers of atherosclerosis that has not been studied on the popliteal artery. An increase in intima-media thickness of the common carotid artery is also considered to be an indication of early stages of atherosclerosis. With use of ultrasound, the diameter of the popliteal artery was measured at rest and during reactive hyperemia after 5-minute arterial occlusion. Subsequently, the intima-media thickness was measured in left common carotid arteries in 27 patients with hyperlipidemia, in 10 patients with confirmed coronary artery disease, and in 20 healthy individuals. In healthy individuals, popliteal artery diameter increased by mean of 6.6 +/- 3.5% (p < 0.01) in relation to hyperemia. In patients with hyperlipidemia before therapy and in patients with coronary disease, no increase in diameter occurred (mean, 0.44% and -1.6%, respectively). The difference between healthy individuals and patients was statistically significant at p < 0.001. The popliteal artery seems to respond similarly to the brachial artery. When comparing the change in popliteal artery diameter and intima-media thickness of common carotid arteries, a strong negative correlation (r = -0.5713, p < 0.001) was observed in all subjects.