Transforaminal lumbar interbody fusion (TLIF) is a relatively new technique of lumbar arthrodesis via posterior transforaminal approach to the disc, indicated mainly in cases of degenerative disc disease, low grade spondylolisthesis and reoperation for disc herniation, especially when there is indication for interbody fusion and posterior decompression. The aim of the study is to asses and evaluates the outcome of posterior instrumeneted transforaminal lumbar interbody fusion as a surgical treatment modality for symptomatic lumbar degenerative disease. this was a clinical trial study, including 20 cases of symptomatic degenerative lumbar disease who have failed medical treatment which includes one or more of the following: more than 40-year-old, having radiological evidence of lumbar degenerative disease whether stable or unstable. The duration of the study ranged from 6-12 months. Oswestry Disability Index (ODI) at baseline was ranged between 42 – 80 with a mean value of 61.65±11.380 and it was decreased significantly after 1 year of surgery with a mean value of 35.35±11.417. VAS score at baseline was ranged between 4 – 9 with a mean value of 6.80± 1.609 and it was decreased significantly after 1 year of surgery with a mean value of 0.75±0.910. TLIF is a technique which offers a simple, safe and effective treatment for degenerative lumbar spine disorders with great improvement of life quality of cases with surgery satisfaction.