A 63-year-old man developed acute cauda equina syndrome due to fat graft compression. Following decompressive laminectomy and posterior instrumented fusion with pedicle screw fixation for spinal stenosis of L5 and S1 vertebral levels, free fat grafting was performed to cover the exposed dura. The patient developed gradual neurological deficit three days postoperatively. This started with sensory loss and weakness of the affected dermatomes and myotomes, followed by bowel incontinence on the 12th postoperative day. Intraoperatively, significant dural compression by the fat graft was confirmed. Immediate removal of the fat graft resulted in recovery from cauda equina syndrome.