Objective We report a novel postmastoidectomy hyperacusis syndrome (PMHS) in patients who have had cortical mastoidectomies and experience hyperacusis to stimuli involving touch of the pinna and periauricular area. This report aims to describe the clinical characteristics of patients predisposed to this disabling complication after mastoid surgery and describes surgical treatment with mastoid cortex resurfacing with hydroxyapatite bone cement. Patients Three patients who have undergone intact canal wall mastoidectomies for nonchronic middle ear-related pathologies all reported a similar constellation of postoperative symptoms. None of the patients had any ossicular chain or middle ear abnormalities, and none had preoperative conductive hearing loss. All patients reported disabling hyperacusis related to light touch stimuli in the periauricular area. On examination, all three patients demonstrated synchronous movement of the tympanic membrane when the postauricular area was palpated. Intervention(s) After a period of observation, none of the patients noted any improvement to their symptoms. Resurfacing of the mastoid cortex with hydroxyapatite bone cement was performed in all patients. Main Outcome Measure(s) Presence of touch-induced hyperacusis and audiometry was assessed postoperatively. Patients were also examined for synchronous movement of the tympanic membrane with palpation of the postauricular area. Results All patients experienced complete resolution of touch-induced hyperacusis postoperatively. Pure-tone audiometric hearing thresholds remained unchanged after mastoid cortex resurfacing, and there was no longer tympanic membrane movement with palpation of the postauricular area. Conclusions PMHS can occur in patients after cortical mastoidectomy when there is no history of ossicular chain or history of chronic middle ear disease or middle ear abnormalities. PMHS can cause significant distress to patients and remain underrecognized unless synchronous tympanic membrane movement is specifically examined for. Treatment via mastoid cortex surfacing with hydroxyapatite bone cement is safe and effective.