Background/Aims: We investigated the clinical characteristics and prognosis of elderly patients with acute lymphoblastic leukemia (ALL). Methods: We reviewed the clinical data, laboratory findings, bone marrow findings, and cytogenetic analysis of elderly patients (≥ 60 years) with ALL, and data of an additional 101 younger adult patients (< 60 years) with ALL were reviewed for comparison. Results: Twenty-six elderly patients (≥ 60 years) and 101 younger adult patients (< 60 years) with ALL were retrospectively enrolled. The median follow-up duration was 6.0 months (range, 0.4 to 113.2) in the elderly patients and 21.7 months (range, 1.0 to 122.7) in the adult patients. In total, 34.6% (9 patients) of the elderly patients and 24.8% (25 patients) of the adult patients had Philadelphia chromosome positive ALL. The overall complete remission (CR) rate was much higher in the younger than in the elderly patients (94.1% vs. 57.7%, p < 0.001). The median overall survival (OS) of the younger patients (< 60 years) was 26.3 months, whereas that of the elderly patients (≥ 60 years) was 10.3 months (p = 0.003). In the elderly patients with ALL, T cell lineage and the presence of lymphadenopathy were significant prognostic factors for OS in a univariate analysis (p = 0.033 and 0.041, respectively). Conclusions: The outcomes of Korean elderly patients with ALL were poor, and the shorter OS was mainly due to the low CR rate. T-cell lineage and the presence of lymphadenopathy were significant prognostic factors in Korean elderly patients with ALL.