The purpose of this study was to examine the association of conjugal circumstances and social support with carotid atherosclerosis. The subjects were 212 men randomly selected from those (N = 4,853) aged 50-60 years, living in Kuopio and a nearby residental area in eastern Finland. Social network and support levels were assessed with a structured 34-item questionnaire. Conjugal circumstances were constituted by cohabition or otherwise. Intima media thickness of the carotid artery (IMT) was chosen to designate atherosclerosis, and determined by quantitative B-mode ultrasonography. The analyses showed that the men living alone had greater common carotid (p = 0.008) and carotid bifurcation (p = 0.011) IMT values than their cohabiting counterparts. The differences remained significant even when the confounding factors (age, health status and education level) and potential intervening factors (saturated fat consumption and smoking) were allowed for. Of the social support subindices, strong adequacy of emotional support (p < 0.001) and of the social network subindices, strong social anchorage (p = 0.031) were correlated to increased common carotid IMT. The present data suggest that conjugal circumstances are an independent social factor predicting carotid atherosclerosis.