A 54-year old male, current smoker, was admitted to the emergency unit with lingular pneumonia. The follow-up chest CT and bronchoscopy showed an airway-blocking intrabronchial tumour. After surgical resection, pathological examination established the diagnosis of a bronchial mucous gland adenoma. The bronchial mucous gland adenoma is an extremely rare and benign lung tumour. It is composed of mucus-containing acini lined with cuboidal cells without pleomorphism. Total surgical resection is usually required for complete diagnosis and treatment. The main differential diagnoses are a low-grade mucoepidermoid carcinoma and a mucinous cystadenoma of the lung. This case highlights the importance of a complete lung workup after acute pneumonia in patients with a history of smoking, including the CT scan and bronchoscopy.