165 patients with diabetes mellitus were found in 1748 CVA patients who were admitted in SNUH from 1978 to 1982. To know the characteristics of stroke occuring in diabetic patients and to clarify the pathogeneti.c rrechanisms invaived in high morhidity and mor tality found in these patients, we studied 130 cases nt random in 165 cases. Diabetiic patients had hig- her prevalence of cerebral infarction and showed higher mortality than the nondiabetic patients. Preaence of microvascular complicatior. Seems to be an important determinant of prognosis in these patients. Hyperosrnolarity occur frequently in diabetic patients with strok, and make an important complication in these patients.