Introduction: Pulmonary fungus ball is a rare complication in pre-existing pulmonary cavitary lesions, due to some chronic pulmonary diseases including tuberculosis, lung abscess and sarcoidosis. Fungus ball is mostly caused by aspergillus. In many patients, fungus ball is asymptomatic, but in a significant number of them it can develop cough and hemoptysis, which may be massive and fatal. The cornerstone of assessment is chest imaging, along with sputum culture or aspergillus antibody in patient's serum. The purpose of this report is increment in attention to this complication in patients with previous pulmonary tuberculosis (TB). Case Presentation: The patient was a 23-year-old woman with chief complaint of fever, cough and hemoptysis, who was hospitalized in the Infectious Diseases Ward of Farshchian Sina hospital in March 2016. She had a history of anti-TB therapy from two years before. Sputum and bronchoalveolar lavage (BAL) were negative for cytology and Mycobacterium tuberculosis, but cultures of both samples were positive for Aspergillus niger. Her lung contrast-enhanced computerized tomography (CECT) scan revealed the presence of a fungus ball inside the upper lobe cavity of right lung. After lobectomy, fungal mass was confirmed by histopathology. Conclusion: In patients with pulmonary complaints (especially hemoptysis) and history of cavitary pulmonary tuberculosis, the differential diagnosis of community-acquired pneumonia, lung abscess, reactivation of tuberculosis and lung cancer as well as fungal infections should be considered.