This study was performed to analyze the clinical, radiological results of 70 patients with isthmic spondylolisthesis and 30 patients with degenerative spondylolisthesis who were underwent with wide decompression, reduction with transpedicular screw system and posterolateral fusion from Mar. 1990 to Dec. 1995. In this study we excluded posterior lumbar interbody fusion, circumferential fusion or decompression method for sondylolisthesis. The mean follow up duration was 29 months. The most common level was L5-Sl in isthmic group (36 patients, 51%), and L4-5 in degenerative group (23 patients, 77%). The clinical result were analyzed according to Kirkaldy-Willis criteria. The satisfactory result were obtained 90% in each group. Screw failure occured in unstable level with severe slip angle, so anterior column support may be recommended in this group. Pedicle screw fixation and wide decompression augmented with posterolateral bone graft is a satisfactory alternative method for degenerative and isthmic spondylolisthesis.