On general principle, spondylolisthesis does not need surgical treatment but special features may arise in any such case to change the clinical picture and to indicate the necessity for operative intervention. There have been described a number of techniques and their combinations in the treatment of spondylolisthesis. Despitc continuing efforts to develop better techniques of lumber fusion, failure has been relatively common. In 1953, Watkins dcscribed a lateral approach to the transverse processes. Rombold recently described a lateral mass fusion of a single level for spondylolisthesis using extensive autogenous iliac grafts. He reported 96% roentgenographic fusion. It is the purpose of this paper to review a series of adults with symptomatic spondylolisthesis (16 cases) who were surgically treated by posterolateral fusion. 1. The site incidence of spondylolisthesis was 68.8%(11 cases) in L-5, 25%(4 cases) in L-4 and 6.2% (1 case) in L-4 & L-5. 2. Satisfactory resutts according to Gills criteria was 94% (15 cases). 3. In follow-up study, the younger the adult, the better the clinical results. 4. The fusion rate of intervertebral joint in roentgenographic finding was 100%. 5. There were no significant differences in duration and result of solid fusion between cases applied with hip spica cast and lumbosacral back brace or Norton-Brown brace.