Aim and objectives: The aim of the present study is to compare the effect of oral pre operative acelofenac , flurbiprofen, Ketrolac vs placebo on the success of inferior alveolar nerve blocks (IANB) in patient with irreversible pulpitis. Material and methods: For this study, 40 patients with irreversible pulpitis of mandibular posterior teeth weredivided into 4 groups Group 1: acelofenac, group 2: flurbiprofen, group 3: ketorolac and group D: placebo after assessing the pain scores using visual analogue scale. Medication was given 30 minutes before the procedure and IANB was administered using 2% Lignocaine. Signs of anesthesia was assessed after 15 minutes following which teeth were tested with cold spray. Access cavities were prepared and success of IANB was assessed as absence of pain during procedure. Results and Conclusion: the results showed increased depth anesthesia when preoperative NSAIDS were given as compared to placebo.