Objective To assess the effectiveness of surgical interventions for lumbar isthmic spondylolisthesis in adults.Methods RCTs of surgical treatment for adult lumbar isthmic spondylolisthesis were identified from specialized trials registered in Cochrane Back Group, The Cochrane Library (Issue 2, 2004)，additional electronic search (including MEDLINE (1966 to 2004)，EMBASE (1980 to 2004) and CBM), handsearching for Chinese journals. Two reviewers assessed the quality of the trials and extracted data independently. Meta analysis was conducted using RevMan 4.2. Results Four published trials including a total of 277 patients were included. Three trials compared different operative procedures and one trial considered conservative versus surgical treatment for lumbar isthmic spondylolisthesis in adults. Two trials had limitations of trial design which at times gave considerable potential for bias. As very few studies and patients were included, and different score criteria were used to assess the clinical outcomes in the review, we decided to provide a descriptive summary only. All trials drew a conclusion that lumbar posterolateral fusion for adult isthmic spondylolisthesis could relieve pain and improve clinical outcome. There was no significant difference in fusion rate and improvement of clinical outcomes between different operative procedures. One trial showed that the lumbar posterolateral fusion could improve function and relieve pain more efficiently than an exercise program. Three trials indicated there was no difference in fusion rate and improvement of clinical outcomes between different operative methods. One trial suggested that instrumented posterolateral fusion did not improve fusion rate but increased complication rates, operation time and bleeding loss. Two trials considered the role of decompressive laminectomy and reached a conflicting conclusion. Conclusions There is no adequate evidence about the most effective technique of treatment for adult lumbar isthmic spondylolisthesis. There is limited evidence that the lumbar posterolateral fusion for adult isthmic spondylolisthesis can efficiently relieve pain and improve clinical outcome. There is no evidence that the use of pedicle screw fixation can improve the fusion rate or the clinical outcome. At present, there is no enough evidence available from randomised trials to support the routine clinical use of instrumented fusion for lumbar isthmic spondylolisthesis in adults. As very few studies and patients were included in the review, it was cautious to draw any conclusions from the review. More trials with high quality on methodology are needed.