Study Design. A prospective analysis of the clinical outcome of a consecutive series of patients treated with posterior lumbar arthrodesis. Preoperative data were collected retrospectively by chart review. Objectives. To measure by independent review the clinical outcome of posterolateral intertransverse fusion as a treatment for discogenic low back pain in a highly selected group of patients. Summary of Background Data. Although numerous studies have reported on the surgical management of degenerative disc disease, they have been difficult to interpret because they lack patient-oriented outcome assessment and objective pain measurement criteria, independent review, and include patients with diagnoses other than degenerative disc disease. Methods. Between 1991 and February 1993 all patients seen by a single surgeon, evaluated with magnetic resonance Imaging and discography; and treated with posterolateral lumbar fusion were reviewed by independent investigation. Outcome was assessed in the areas of radiographic fusion, pain, function, and patient satisfaction. Results. Twenty-three patients (12 women, 11 men; 100% follow-up an average of 47 months after surgery [range, 24-84 months]) met the inclusion criteria. Overall, 39% had a good or excellent result, 13% fair, and 48% poor. Nine of 10 patients receiving worker's compensation had poor result; four of five patients with radiographic pseudarthrosis had a poor result. Statistically significant improvement in the visual analogue significant improvement in the visual analogue scale was noted in the good and excellent group (P = 0.0001) and the fair group (P = 0.002) with no change in the poor group. Patients out of work more than 3 months before surgery tended to have poor results. Overall, 56% of patients were extremely satisfied with the result of their surgery. Conclusions. Posterolateral intertransverse fusion can be used to successfully manage chronic discogenic back pain. However, patient selection remains a challenge, and successful outcome appears to be limited in the subset of patients receiving worker's compensation and those chronically disabled. Prospective and randomized study with objective pain criteria, independent review, and patient-oriented outcome is recommended.