We investigated the relation between the serum concentration of HGF and carotid atherosclerosis. Serum concentrations of HGF were measured in 128 in-patients (mean age, 74 +/- 11 years) free from cardiac, liver and renal diseases, in addition to lung diseases, in the Medical Department of Nomura Municipal Hospital between August, 2000 and June, 2001. Carotid intima-media thickness (IMT) was evaluated by ultrasonography with a 7.5 MHz linear type B-mode probe. The results showed a significantly positive correlation between serum age and HGF concentrations in patients with carotid atherosclerosis (IMT > 1.0 mm) (r = 0.391, p = 0.005). On the other hand, there was no significant correlation between age and serum HGF concentration in those without carotid atherosclerosis (IMT </= 1.0 mm) (r = 0.157, p = 0.173). A general linear model analysis for HGF adjusted with other risk factors showed that the age-carotid atherosclerosis interactions were significantly associated with serum HGF (F [1.114] = 6.193; p = 0.014), in addition to age, systolic blood pressure (SBP), aniti-hypertensive drug use, diabetes mellitus and carotid atherosclerosis. In contrast, multiple regression analysis showed that serum HGF (beta = 0.160, p = 0.033) was independently associated with carotid atherosclerois, in addition to gender, age, SBP and HDL-cholesterol. These results suggest that increased serum HGF concentrations were associated with carotid atherosclerosis, independent of known risk factors for atherosclerosis.