DISCUSSION: Endobronchial actonomycosis is caused by Actinomyces spp., an anaerobic Gram-positive bacteria that normally colonizes the digestive and genital tracts. Pulmonary actinomycosis is more common in males, and results from aspiration of oropharyngeal or gastrointestinal contents. Respiratory symptoms include cough, sputum production, and pleuritic chest pain. Laboratory data will generally be normal. Diagnosis can be challenging, as up to 25% of cases are initially misdiagnosed as malignancy. Diagnostic properties include positive culture and demonstration of sulphur granules, with clinical and radiographic correlation. Fiberoptic bronchoscopy is usually non-diagnostic unless there is clear endobronchial lesion which is biopsied. The lesion will demonstrate an irregular submucosal tumor with granular thickening that is partially obscuring the bronchi. Treatment entails 6 months of penicillin therapy, with tetracycline and erythromycin being second line agents.