Background: In the endodontic, one of the most damaging and frightening experience is precipitation of pain, during or after the treatment for both patient and clinician. The present study was conducted to assess the effect of preoperative intraoral cryotherapy application on the success rate of inferior alveolar nerve blocks in patients with symptomatic irreversible pulpitis. Materials & Methods: 120 patients age ranged 20-50 years with diagnosis of symptomatic irreversible pulpitis of mandibular molars in both genders were randomly divided into 2 groups of 60 each. Group I comprised of control group and group II received cryotherapy. Before the treatment, all the patients rated their pain on a 170-mm Heft-Parker VAS. Results: There were 35 males and 25 female sin group I and 28 males and 32 females in group II. 36 was involved in 24 cases, 37 in 10, 46 in 18 and 47 in 8 cases in group I and 36 in 21, 37 in 13, 46 in 19 and 47 in 7 cases in group II. The difference was significant (P< 0.05). The mean VAS in group I patients was 110.2 and in group II patients was 109.3. The difference was non- significant (P> 0.05). Conclusion: Intraoral cryotherapy application increased the success rate of inferior alveolar nerve block in mandibular molar teeth with symptomatic irreversible pulpitis. Key words: Cryotherapy, mandibular molar, VAS