Four randomized controlled trials were included in this meta-analysis investigating the efficacy of instrumented and noninstrumented fusion in the treatment of lumbar spondylolisthesis. Of primary concern was how these treatments compared in functional disability. Secondary outcomes included pain, patient-reported satisfaction, and fusion success. Analysis of data on functional disability revealed a greater change in ODI from baseline in noninstrumented cases, although the analysis was limited by heterogeneity and a sensitivity analysis. No significant differences were noted in the analyses on pain and satisfaction. Fusion success was significantly greater with instrumented fusion.