BACKGROUND. There is a clear east-west difference in coronary heart disease (CHD) mortality and incidence in Finland, people living in east Finland having higher CHD rate. A study of Finnish immigrants to Sweden has suggested that a long stay in Sweden would be associated with reduced CHD risk. AIM. To determine whether structural and functional markers of subclinical atherosclerosis differ between men originating from east and west Finland, and whether migration to Sweden influences subclinical atherosclerosis. METHOD. Carotid intima-media thickness (IMT) and brachial artery flow-mediated dilatation (FMD) with high-resolution ultrasound and a set of cardiovascular risk factors were measured in 76 middle-aged male twin pairs (55 pairs from east and 21 pairs from west Finland) discordant for migration to Sweden. RESULTS. Among men living in Finland, IMT was significantly higher in men originating from east Finland compared to those from west Finland (0.796 ±0.212 versus 0.704 ±0.123 mm, P = 0.02). A similar east-west difference was observed in men who had migrated to Sweden (0.766 ±0.220 versus 0.686 ±0.089 mm, P = 0.03). The east-west difference in IMT persisted after adjustment for the major traditional cardiovascular risk factors. No east-west difference was seen in FMD. Smoking, Framingham risk score and physical activity had a greater impact on IMT in men originating from east compared to west Finland. CONCLUSIONS. Men originating from east Finland, irrespective of their current residence, have a greater degree of subclinical atherosclerosis and they may be more susceptible to the impact of conventional cardiovascular risk factors than men originating from west Finland.