Objectives/Hypothesis:To evaluate the anti‐adhesive and anti‐inflammatory effects of sodium hyaluronate–carboxymethylcellulose (HA‐CMC) on postoperative hearing improvement and complications during tympanomastoid surgery.Study Design:Prospective controlled clinical trial.Methods:We evaluated 287 patients who underwent type I tympanoplasty, with or without canal wall up mastoidectomy, between January 2007 and June 2010. Postoperative hearing and complications were compared in the 143 patients who received Gelfoam soaked with HA‐CMC during myringoplasty and the 144 patients who received Gelfoam only.Results:There were no significant between‐group differences in sex, age, and preoperative hearing status. However, average postoperative air‐bone gap (13.7 ± 8.5 dB vs. 17.2 ± 9.9 dB) and the number of air‐bone gaps smaller than 10 dB (40.6% vs. 24.3%) were significantly improved in the HA‐CMC compared with the control group. In addition, the rates of re‐otorrhea, reperforation of the tympanic membrane (TM), postoperative TM adhesion, and reoperation were lower in the HA‐CMC than in the control group without significances.Conclusions:These findings suggest that combined application of Gelfoam with HA‐CMC may be beneficial in patients undergoing tympanomastoid surgery. Laryngoscope, 2012