BACKGROUND: Interlaminar epidural steroid injection (ILESI) is commonly performed nonsurgical intervention in patients with lumbar spinal stenosis. There is no consensus regarding appropriate intervertebral level of ILESI that leads to maximum effectiveness. In this study, we compared the efficacy of ILESI on pain relief and functional improvement when given at the level of maximum stenosis versus at nearby less stenotic levels in patients of lumbar canal stenosis. MATERIALS AND METHODS: In this study, 80 patients were randomly allocated to two groups: Group A received lumbar ILESI of 5mL bupivacaine (0.25%), 2 mL methylprednisolone acetate (40 mg/mL), and 1 mL normal saline at maximal stenotic intervertebral level, and Group B received the same drugs at less stenotic level, two intervertebral spaces cephalad or caudad to maximum stenosis. The effects were evaluated by Numeric Pain Rating Scale (NPRS) and Oswestry Disability Index (ODI) at 2, 6, and 12 weeks after the intervention. RESULTS: Results of 30 patients in each group were assessed. Pain relief and improvement in ODI were observed in both groups after injection. Group A had significantly better pain relief at 2 and 4 weeks after injection. The ODI at 2, 6, and 12 weeks after injection was significantly lower in Group A as compared to Group B. CONCLUSION: ILESI at maximum stenotic intervertebral level leads to better pain relief and functional improvement as compared to injection given at less stenotic level in lumbar spinal canal stenosis.