We assess the effect of lumbar fusion (LF) in reducing disability among patients with chronic low back pain (CLBP) compared with conservative treatment and to weigh the clinical significance of this effect. We conducted a random-effect meta-analysis on the basis of a systematic review with research quality grading according to Grading of Recommendations Assessment, Development and Evaluation (GRADE). The studies included were retrieved from MEDLINE and Cochrane CENTRAL databases from 1990 till January 2013. Randomized or nonrandomized controlled studies were included if the study participants had a history of CLBP because of degenerative spinal diseases and had been treated with LF. A study was included if it compared LF with conservative treatment. The outcome measure was a change in the Oswestry Disability Index (ODI) score during a follow-up. The meta-analysis included data on 666 patients (402 cases) who participated in four randomized–controlled trials. The ODI score reduced in the LF and the control groups. The mean reduction in the ODI score in the follow-up of 1.5 years was −2.91 (95% confidence interval −6.66 to 0.84) in favor of LF. The difference between groups was statistically and clinically insignificant. Test for heterogeneity indicated that study imputation would favor LF but the imputed result would still be clinically insignificant with an estimated corrected reduction of ODI score of −5.51 (95% confidence interval −5.78 to −5.24). There is strong evidence that LF is not more effective than conservative treatment in reducing perceived disability because of CLBP among patients with degenerative spinal diseases. It is unlikely that further research on the subject would considerably affect this conclusion.