Cohorts of diabetic (n = 121) and non-diabetic (n = 584) patients were prospectively followed for up to ten years after having suffered from a stroke. All but six of the diabetic patients had Type 2 (non-insulin-dependent) diabetes mellitus. The diabetic patients had more risk factors associated with stroke: heart failure (p less than 0.001) and angina pectoris (p less than 0.001), than the non-diabetic patients. Neither body mass index nor blood pressure levels differed between the groups at admission. Haematocrit levels were higher in the diabetic group (p less than 0.01). The diabetic patients were more commonly afflicted by cerebral embolism and to a lesser extent by transient ischaemic attacks than the non-diabetic patients. When calculated by log-rank tests, the diabetic group had an increased risk of death (p less than 0.001), recurrent stroke (p = 0.001), and of myocardial infarction (p = 0.001) after the initial stroke. Autopsy-verified causes of death between the groups did not differ significantly, although half of all deaths during the period one to six months after stroke were caused by pulmonary embolism in the diabetic group. Thus, diabetes increases the risk of death after a stroke, and it also increases among stroke survivors the risk of recurrent stroke and myocardial infarction.