OBJECTIVE: To investigate the length of hospital stay (LOS) after stroke using the database of the Korean Health Insurance Review & Assessment Service. METHODS: We matched the data of patients admitted for ischemic stroke onset within 7 days in the Departments of Neurology of 12 hospitals to the data from the database of the Korean Health Insurance Review & Assessment Service. We recruited 3,839 patients who were hospitalized between January 2011 and December 2011, had a previous modified Rankin Scale of 0, and no acute hospital readmission after discharge. The patients were divided according to the initial National Institute of Health Stroke Scale score (mild, ≤5; moderate, >5 and ≤13; severe, >13); we compared the number of hospitals that admitted patients and LOS after stroke according to severity, age, and sex. RESULTS: The mean LOS was 115.6±219.0 days (median, 19.4 days) and the mean number of hospitals was 3.3±2.1 (median, 2.0). LOS was longer in patients with severe stroke (mild, 65.1±146.7 days; moderate, 223.1±286.0 days; and severe, 313.2±336.8 days). The number of admitting hospitals was greater for severe stroke (mild, 2.9±1.7; moderate, 4.3±2.6; and severe, 4.5±2.4). LOS was longer in women and shorter in patients less than 65 years of age. CONCLUSION: LOS after stroke differed according to the stroke severity, sex, and age. These results will be useful in determining the appropriate LOS after stroke in the Korean medical system.