Introduction. Recently various type of spinal instrumentation was applied, and they are essential in modern spinal fusion surgery. Whereas several authors reported increased possibility of complication and degeneration on adjacent segment. We tried PLIF without instrumentation with box type intervertebral cages. Method. Forty-one cases of degenerative lumbar diseases were treated by PLIF with carbon cages without spinal instrumentation. There were 17 males and 24 females, and age averaged 71.4 years. Thirty-two cases were degenerative spondylolisthesis, five were spinal stenosis, and four were disc herniation. Single PLIF was performed on forty cases, and double segment in one, with additional decompression on other segment in twenty. Bilateral facet joint were preserved to avoid lateral instability. Two pieces of cage were inserted with local bone graft. Post-op. follow-up period were 12 to 24 months, 15 months on average. Result. JOA score (29 pts on full mark) averaged 12.7 pts before the operation and was 25.4 pts at the F/U. Recovery ratio averaged 77.9%. Clinical result was excellent in 27 with more than 75% of R/R. One case showed symptomatic non-union, and additional instrumentation was applied after one year. Thirty-three cases (80%) showed solid bone union after one year, and eight cases were classified as non-union. Whereas early cage migration with vertebral collapse was seen on fourteen, and union with collapse was seen in eight. These conditions showed less clinical outcome. Conclusion. Stand alone PLIF resulted in good clinical results with box type cages. Stand alone PLIF is less invasive method and minimize chance of complication. Conflicts of interest. None. Sources of funding. None