Aspergillus mastoidits and skull-base osteomyelitis are extremely rare, even in immunocompromised patients. We report a case of an 81-year-old immunocompetent man, who underwent a mastoidectomy because of unexplained, progressive otalgia in spite of a noninflamed and air-containing middle-ear space. Histopathology yielded Aspergillus fumigatus. When confronted with otitis with an unexpected clinical course a high index of suspicion is required to facilitate early diagnosis and appropriate therapy of a potential lethal Aspergillus infection, even in immunocompetent patients. This seems to be more so in older patients with an open middle-ear cavity and/or when there is facial nerve involvement.