Indirect decompression using oblique lateral interbody fusion (OLIF) improves spinal canal dimensions by reducing spondylolisthesis and restoring intervertebral disk height in patients with degenerative lumbar diseases. However, the clinical significance of these radiological improvements has not been fully evaluated in the literature. To examine the relationship between the clinical and radiological outcomes following OLIF, the authors prospectively studied 41 patients who underwent single-level OLIF with percutaneous pedicle screw fixation for lumbar degenerative disease, including degenerative and spondylolytic spondylolisthesis and spinal stenosis with disk height loss. Clinical scores were obtained preoperatively and at 1 year postoperatively using multiple questionnaires. Radiological outcomes were evaluated using plain radiographs, computed tomography (CT) scans, and magnetic resonance imaging (MRI) at 1 year postoperatively. Following a single-level OLIF, all categories of clinical scores showed statistically significant improvement. Rate of cage subsidence was 14.6% and 31.7% at 1 week and 1 year postoperatively, respectively. Patients with subsidence had higher Oswestry Disability Index (P=.026) scores and lower physical composite summary scores on the Short Form-36 Health Survey (P=.007). On CT scan, 28 (68.3%) patients showed a complete interbody fusion and 13 (31.7%) had intermediate fusion. All parameters from the MRI, except for foraminal width, showed significant improvement at 1 year postoperatively. The improvement ratio of foraminal height was associated with the percent improvement of lower-extremity radiating pain (Pearson coefficient=0.384; P=.013) and the walking ability score of the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (Pearson coefficient=0.319; P=.042) at 1 year postoperatively. Restoration of foraminal height while preserving the endplates is associated with favorable results following OLIF. [Orthopedics. 2020;43(x):xx-xx.].