Non specific low back pain affects 85% of patients who present to primary care and is one which cannot be reliably attributed to a specific disease or spinal abnormality. Physical therapy modalities are frequently used for its management but the best evidence for the efficacy and cost effectiveness of the treatment is provided by well designed systematic reviews and randomized controlled trials. The study includes recent evidences for the same from Cochrane library. The results have revealed the efficacy of superficial heat, patient education and advice to stay active than bed rest in acute LBP. Graded activity exercise, superficial heat, massage, physical conditioning and individual patient education are effective in sub acute LBP. Exercise, massage, spinal manipulative therapy, back schools, physical conditioning programs are moderately effective in chronic LBP. Tens and traction are found to be ineffective in LBP besides the duration of symptoms. Evidence is inconclusive about the role of laser, ultrasound, lumbar supports, superficial cold, use of insoles, advice on manual material handling and use of assistive devices. Multidisciplinary bio psychosocial rehabilitation and behavioral therapy have been found to be at least moderately effective in sub acute to chronic LBP. But most of the studies were found to be inadequate in terms of poor methodological quality. In addition the heterogenecity of the non specific LBP population cannot be ignored. There is a need to establish a classification system for non specific LBP that would allow determining how subgroups differ in terms of natural course and whether treatment and management strategies could be tailored to each subgroup. This should be followed by designing future trials of high methodological quality.