Munchausen syndrome is a pattern of abnormal behavior in which patients repeatedly present with symptoms that have no organic basis and are intentionally simulated or produced in order to assume the sick role and gain admission to the hospital. A 25-year-old white woman presented to our adult cystic fibrosis (CF) program and gave a detailed history consistent with a diagnosis of CF, a complicated disease with multiorgan involvement that is difficult to feign. However, discrepancies in her history were noted and objective measures of disease were inconsistent, including evidence of a fabricated sweat chloride result. We describe the classic characteristics of Munchausen syndrome that our patient exhibited, and report this unusual presentation of Munchausen syndrome to be consistent with the recommendation of reporting such cases to other physicians. Such knowledge is likely to result in less harm to the patient through unnecessary testing and treatment.