We investigated the determinants of maximal intima-media thickness of common carotid arteries in a population-based sample of 1224 Eastern Finnish men aged 42, 48, 54 or 60 years. A high-resolution B-mode ultrasonographic examination was performed as part of the Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD). The maximal intima-media thickness (IMT) varied between 0.48 mm and 4.09 mm (mean value +/- SD, 0.94 mm +/- 0.38 mm). Age (standardized partial coefficient, beta = 0.238, P less than 0.0001), ambulatory pulse pressure (beta = 0.130, P less than 0.0001), cigarette-years of smoking (beta = 0.125, P less than 0.0001), serum LDL cholesterol concentration (beta = 0.125, P less than 0.0001), history of ischaemic heart disease (beta = 0.125, P less than 0.0001), pre-exercise systolic blood pressure (beta = 0.070, P = 0.0113) and diabetes (beta = 0.068, P = 0.0072) were most strongly associated with IMT. This study confirms the role of systolic blood pressure, smoking and serum LDL cholesterol levels as major risk factors for increased carotid intima-media thickness.