Objective. To characterize the value of low-molecular-weight DNA in blood plasma and cerebrospinal fluid for the diagnosis of acute stroke of ischemic and hemorrhagic types early after the onset of the disease. Material and methods. DNA from plasma and cerebrospinal fluid was isolated by phenol deproteinization, analyzed by gradient polyacrylamide electrophoresis. Content of low-molecular-weight DNA was determined on the electrophoregram by comparison with standards. Results. Authors discovered the differences in the changes in the content of low-molecular-weight DNA in the blood plasma of patients with acute ischemic and hemorrhagic types of cerebrovascular accident within 3 days after onset. Patients with hemorrhagic stroke were characterized by an increase in low-molecular-weight DNA after 3 hours, while patients with ischemic stroke after 24 hours from onset. Low-molecular-weight DNA was also detected in the cerebrospinal fluid of patients with ischemia during the first day of the disease. Conclusion. The results indicate a role of apoptosis in the formation of ischemic lesion.