Objective: The purpose of this case report is to describe a patient with an L5/S1 posterior surgical fusion who presented to a chiropractic clinic with subsequent low back and leg pain and was treated with Cox decompression manipulation. Clinical features: A 55-year-old male postal clerk presented to a private chiropractic practice with complaints of pain and spasms in his low back radiating down the right buttock and leg. His pain was a 5 of 10, and Oswestry Disability Index score was 18%. The patient reported a previous surgical fusion at L5/S1 for a grade 2 spondylolytic spondylolisthesis. Radiographs revealed surgical hardware extending through the pedicles of L5 and S1, fusing the posterior arches. Intervention and outcome: Treatment consisted of ultrasound, electric stimulation, and Cox decompression manipulation (flexion distraction) to the low back. After 13 treatments, the patient had a complete resolution of his symptoms with a pain score of 0 of 10 and an Oswestry score of 2%. A 2-year follow-up revealed continued resolution of the patient's symptoms. Conclusions: Cox chiropractic decompression manipulation may be an option for patients with back pain subsequent to spinal fusion. More research is needed to verify these results.