The incidence of carotid artery disease and cerebrovascular symptoms were determined in 102 consecutive patients with peripheral arterial disease. Symptoms were correlated with risk factors of age, hypertension, smoking and diabetes and with the extent of disease at the carotid bifurcation. The incidence of stroke with permanent neurological deficit was twice as high in diabetics as in non-diabetics with equivalent atherosclerotic vascular disease (p less than .05). In women, the incidence of stroke was three times higher in diabetics (p less than .02). The number of transient ischemic attacks was significantly higher in non-diabetics (p less than .02). The total number of ischemic episodes in diabetics and non-diabetics was equivalent. This indicates that diabetics are more prone to irreversible destruction of ischemic brain tissue regardless of the nature of the circulatory disturbance.