OBJECTIVE: Malignant middle cerebral artery (MCA) infarction occurs in 10% of all ischemic strokes and these severe strokes are associated with high mortality rates. Recent clinical trials demonstrated that early decompressive craniectomy reduce mortality rates and improves functional outcomes in healthy young patients (less than 61 years of age) with a malignant infarction. The purpose of this study was to assess the efficacy of decompressive craniectomy in elderly patients (older than 70 years of age) with a malignant MCA infarction. METHODS: Between February 2008 and October 2011, 131 patients were diagnosed with malignant MCA infarctions. We divided these patients into two groups: patients who underwent decompressive craniectomy (n = 58) and those who underwent conservative care (n = 73). A cut-off point of 70 years of age was set, and the study population was segregated into those who fell above or below this point. Mortality rates and functional outcome scores were assessed, and a modified Rankin Scale (mRS) score of > 3 was considered to represent a poor outcome. RESULTS: Mortality rates were significantly lower at 29.3% (one-month mortality rate) and 48.3% (six-month mortality rate) in the craniectomy group as compared to 58.9% and 71.2%, respectively, in the conservative care group (p < 0.001, p = 0.007). Age (> or =70 years vs. < 70 years) did not statistically differ between groups for the six-month mortality rate (p = 0.137). However, the pre-operative National Institutes of Health Stroke Scale (NIHSS) score did contribute to the six-month mortality rate (p = 0.047). CONCLUSION: Decompressive craniectomy is effective for patients with a malignant MCA infarction regardless of their age. Therefore, factors other than age should be considered and the treatment should be individualized in elderly patients with malignant infarctions.