Abstract: Objective To investigate the risk factors, clinical manifestations and prognosis of elderly patients with malignant middle cerebral artery infarction(mMCAI). Methods Sixty-six elderly patients with mMCAI were divided into senile group(n=36, ≥80 years old)and elderly group(n=30, 60~<80 years old)according to their age. The clinical manifestations, risk factors of onset, modified Rankin Scale score at discharge and prognosis were compared between the two groups. Results Compared with the elderly group, the ratios of patients with diabetes mellitus, smoking and drinking in the senile group were significantly lower(P<0.05), and the ratio of patients with atrial fibrillation was significantly increased(P< 0.05). There were significant differences in increase degree of National Institutes of Health Stroke Scale(NIHSS)scores, shift distance from midline to contralateral line, pro-B-type natriuretic peptide, matrix metalloproteinase-9(MMP-9)and S100 calcium binding protein(S100b)between the two groups after admission(P<0.05). The incidence of cardiovascular events in the senile group was significantly higher than that in the elderly group(P<0.05). The mortality rate of the senile group was 27.78%, which was significantly higher than 13.33% of the elderly group(P<0.05). Conclusion There are significant differences in the risk factors, clinical manifestations, complications and prognosis between the senile patients with mMCAI and the elderly patients with mMCAI. Therefore, it is of great importance to strengthen the comprehensive treatment for the senile patients with mMCAI. Standardized treatment of hypertension, diabetes, carotid stenosis and other diseases, and strengthened anticoagulant therapy can prevent and reduce the occurrence of cerebral infarction.