Stroke is frequently associated with readmission; moreover, readmission is regarded as an important indicator of the quality of stroke care. Thus, we investigated factors associated with 30-day readmission in patients with stroke in South Korea. We used claims data from 2013 for stroke (I60-I62) patients (n=44 729) in 94 hospitals and classified unplanned readmission according to the Centers for Medicare and Medicaid guidelines. We used multilevel models to investigate patient (age, gender, type of insurance, admission via emergency room, length of stay, type of stroke, Elixhauser Index Score) and hospital (stroke care quality grade, location of hospital, type of hospital, number of doctors and nurses per 100 beds) factors associated with readmission within 30 days of discharge. Among the 44 729 patients admitted due to stroke, 9.2% (n=4124) were readmitted to hospital and 7.6% (n=3379) had unplanned readmissions. Regarding patient characteristics, medical aid and longer hospital stay were associated with 30-day readmission rate. Among hospital factors, patients admitted to a low-grade hospital or a non-capital area hospital were more likely to be readmitted within 30 days of discharge. We identified patient and hospital factors associated with 30-day readmission among stroke patients. In particular, patients admitted to hospitals with higher quality stroke care showed lower readmission rates.