BACKGROUND This study has been designed to investigate the clinical association between gastro esophageal reflux disease (GERD) and chronic otitis media (COM) in adults and also the role of GERD treatment on the outcome of COM surgery. METHODS In a randomized clinical trial, 58 patients with COM who were candidates for surgery were evaluated for GERD and divided in two groups; GERD positive (case) and GERD negative (control) patients. The GERD positive patients were randomized to either receiving medical treatment for GERD or not prior to surgery. The surgical outcomes were assessed at 3 and 6 months after COM surgery in the three groups. RESULTS Fifty-eight (26 males) patients were enrolled. Forty-two (72.4%) of these had GERD according to a validated questionnaire. Three months after surgery auditory recovery in GERD negative patients was significantly higher [16(100%)] than those suffering from GERD [28 out of 42 (66.7%)], p=0.008. The figures remained similar at six months follow up as well (100 % vs. 72.5% in GERD negative and positive patients respectively, p=0.002).In the GERD-positive group, 8 of 18 (44.4%) patients who did not receive GERD treatment before tympanomastoidectomy recovered after three months whereas, while 20 of 24 (83.3%) patients who received GERD treatment recovered during this time (p