The main aims of tympanoplasty are eradication of chronic middle ear disease, repair of the tympanic membrane, and restoration of hearing. Nitrous oxide (N2O) is not a commonly preferred anesthetic agent for tympanoplasty because this agent may increase middle ear pressure and displace the graft. In this study, we researched the surgical outcomes of the underlay tympanoplasty performed with N2O anesthesia. Patients who underwent tympanoplasty were included in this prospective study. A type 1 tympanoplasty was performed in all patients using the underlay technique. Patients were randomized to groups that did and did not receive N2O. Preoperative and postoperative hearing thresholds were evaluated, postoperative pain scores were recorded, and the differences between the groups were statistically evaluated. There were 44 patients who received N2O and 44 who did not. The graft success rate was 93.2% in the N2O-receiving group and 84.1% in the nonreceiving group (P > .05). Hearing levels improved significantly after surgery in each group (P < .05), but the difference between the groups was not significant (P > .05). The postoperative pain score was 3.72 +/- 1.3 in the N2O-receiving group and 4.45 +/- 2.3 in the nonreceiving group (P > .05). Nitrous oxide is a cheap, safe, and readily available anesthetic agent that provides acceptable success rates in patients undergoing tympanoplasty.