Background: Leg pain combined with low back pain (LBP) refers to lumbosacral radiculopathy (LR). It is a common complaint causing global disability. Studies about effect of mobilization of the thoracic spine in treatment of LR are still insufficient. Purpose: to study the impact of thoracic spine mobilization on pain and lumbar mobility in lumbosacral radiculopathy (LR) patients. Methods: Thirty-four male and female patients with unilateral chronic LR, aged from 30 to 45 years were divided equally and randomly to two groups (study and control). Both groups received conventional physiotherapy program. In addition to that, the study group received thoracic spine mobilization as well. The treatment session was lasted 45 to 60 minutes, performed thrice weekly for six weeks. Measurement of back pain and radiated pain were measured with visual analogue scale, whereas lumbar flexion range of motion was measured using Schober test pre and post treatment.  Results:  There were statistically marked improvements in back and leg pain, and lumbar mobility in both groups after treatment (p-value<0.05), in favor of the study group. Conclusion: Thoracic spine mobilization adds a valuable effect to the conventional physiotherapy program in improving back and leg pain, and lumbar mobility in chronic LR patients.