Twenty-seven patients with spondylolysis and back pain were considered for spinal fusion. All patients underwent clinical evaluation, multiplanar computed tomography (CT) and single photon emission computed tomography (SPECT). After clinical evaluation 12 patients were not considered suitable for fusion on clinical grounds. SPECT was normal in these patients. Fifteen underwent a trial of lumbar immobilization and nine of those rendered pain free subsequently underwent spinal fusion. The results of clinical examination, lumbar immobilization, imaging and final outcome were compared in these patients. Those patients rendered pain free by surgery all had positive SPECT scans. Those with persistent pain after surgery had negative scans. This small series suggests a positive relationship between SPECT scanning and patient outcome following fusion. These findings need to be confirmed by larger studies with longer periods of follow-up.