Reported is the outcome for 25 patients in whom spondylolisthesis with radicular pain was treated by posterolateral fusion alone (Group A). These outcomes are compared with those obtained in 23 other patients with the same symptomatology and spondylolisthesis treated by root release and posterolateral fusion (Group B). Most patients had Grade I or II isthmic spondylolisthesis. Results were assessed functionally and radiographically with an average followup of 32 months. Posterolateral fusion in situ provided excellent or good results in 88% of patients according to the modified classification of Stauffer and Coventry. In Group A, radicular pain at exertion disappeared in 92% of patients, and radicular pain at rest disappeared in 88%. In Group B, radicular pain at exertion disappeared in 65% of patients, and radicular pain at rest disappeared in 70%. There was no significant statistical difference between the 2 groups. Resection of the loose lamina and root decompression do not seem to be mandatory. The overall fusion rate was 81%. Instrumentation in case of instability and the use of allografts are advised.