Discogenic low back pain requiring treatment by surgery, can be treated by epidural steroid injection. Epidural injection via transforaminal approach is considered as target-specific requiring the smallest volume to reach the primary site of pathology.The aim of our study was to evaluate the efficacy of injecting different concentrations of corticosteroid in the epidural space via the transforaminal approach. High concentrations of corticosteroids in low volume solutions enhance the therapeutic selectivity, as the injectate reaches only the inflamed nerve root. Thus they are preferred to high volume injections which tend to disperse to different levels.