Objective: As Korea has become a super-aging society, the number of elderly patients with degenerative spinal disease has steadily increased. This study aimed to evaluate the usefulness of oblique lumbar interbody fusion (OLIF) by comparing the results and complications between OLIF and open spinal fusion in elderly patients with degenerative spinal disease.Methods: Thirty-one patients underwent one-level posterior lumbar interbody fusion (PLIF), and 35 patients underwent one-level indirect decompression OLIF. The clinical outcomes of the two patient groups were analyzed using the visual analog scale (VAS) and Oswestry Disability Index (ODI). Through a comparative analysis of pre- and post-operative images, we measured changes in disc height (DH) and foraminal height (FH), and investigated the occurrence of subsidence in each patient group. The cross-sectional area was measured using magnetic resonance imaging pre- and post-operatively in OLIF.Results: The pre-operative VAS and ODI scores were similar between the two groups and tended to improve post-operatively. In the OLIF group, the estimated blood loss (EBL) was significantly lower, DH and FH gains were more frequent, DH and FH maintenance was better, and cage subsidence occurred less frequently. In OLIF, psoas paresis and approach-site hematoma occurred; however, all patients with psoas paresis recovered without further treatment before discharge. In the PLIF group, dural tears occurred in four patients who recovered without revision surgery. Conclusion: OLIF enables indirect decompression, reduced EBL, shorter hospitalization, and lesser subsidence. OLIF is considered a beneficial, minimally invasive surgical method for elderly patients.