We report the case of a 49-year-old woman who developed an endobronchial mycotic pulmonary artery aneurysm (PAA) as a complication of pneumonia. After presenting with patchy infiltrates, she developed right lung atelectasis. A noncontrast chest CT scan revealed a mass in the right hilum, and bronchoscopy identified an obstructing lesion in the right mainstem bronchus. Unfortunately, biopsy caused massive hemorrhage, and the patient died. An autopsy identified a mycotic PAA that had invaded the right mainstem. The case suggests that a contrasted CT scan should be included in the evaluation of endobronchial masses and that PAA should be included in the differential diagnosis of such lesions.