Objective To investigate the effectiveness of direct lateral interbody fusion (DLIF) for lumbar degenerative diseases. Methods A retrospective study was done on 25 cases of lumbar degenerative diseases treated with DLIF between May 2013 and May 2014. There were 15 males and 10 females with an average age of 61.4 years (range, 36-78 years), including 14 cases of lumbar disc herniation, 2 cases of degenerative lumbar scoliosis, 3 cases of lumbar spondylolisthesis, and 6 cases of lumbar instability with spinal stenosis. The disease duration was 8 months to 20 years (mean, 5.7 years). The involved segments included L4, 5 in 10 cases, L3, 4 in 6 cases, L2, 3 in 2 cases, L2-4 in 2 cases, L3-5 in 3 cases, and L2-5 in 2 cases. The operation time, intraoperative bleeding volume, postoperative hospitalization time, and complications were recorded. The visual analogue scale (VAS) and Oswestry disability index (ODI) criteria were used to assess the effectiveness; X-ray film and CT were used to evaluate the bone fusion. Results The mean operation time was 105 minutes (range, 85-155 minutes), and mean intraoperative bleeding volume was 158 mL (range, 80-300 mL). The postoperative hospitalization time was 2-5 days (mean, 3.2 days). All incisions healed by first intension. There was no complication of wound infection, vascular injuries, or intraoperative visceral injuries. All cases were followed up 24.6 months on average (range, 18-30 months). Four cases had iliopsoas weakness, 5 cases had iliopsoas weakness and anterior thigh hypoesthesia, which disappeared within 6 months after operation. No retrograde ejaculation, Cage displacement, or loosening was found after operation. Full bony fusion was observed in 20 segments and partial bony fusion in 12 segments. The mean bony fusion time was 10.8 months (mean, 6-18 months). The height of intervertebral space was significantly increased to (11.98±1.20) mm at 2 days after operation and to (11.80±1.33) mm at last follow-up from preoperative (6.20±0.88) mm (P < 0.05), but no significant difference was found between at 2 days and last follow-up (P > 0.05). At last follow-up, VAS score was significantly decreased to 3.43±0.53 from preoperative 8.26±0.49 (t=26.275, P=0.000), and ODI was significantly decreased to 15.41%±3.91% from preoperative 40.80%±3.10% (t=22.902, P=0.000). Conclusion DLIF is a safe and effective treatment for lumbar degenerative diseases, which has the advantages of less tissue damage, less blood loss, and fast rehabilitation.