Lumbar spine fusion with the use of internal fixation improved clinical results and fusion rate compared to cases without internal fixation. Thirty-two patients were treated surgically for lumbar disease with internal fixation with AO DCP plates and fusion with autogeneous bone grafting posterolaterally at Wonju Christian Hospital. Results of surgery were 87.5% of good to excellent pain relief and 90.6% of solid fusion rate. Complications included 2 cases of screw breakage, 8 cases of screw loosening, one case of screw impingement upon a nerve, 2 case of urinary tract infection, two cases of superficial infection and one case of deep infection. The benefits occuring from augmentation of the fusion with internal fixation using AO DCP plates are positive.