A 29-year-old Japanese man with Duchenne muscular dystrophy was placed on a mechanical ventilator support at 23 years of age and admitted to our hospital at 25 years of age. He had severe neck contracture deviated to the left side which resulted in dysphagia and microaspiration. At 29 years of age, he developed left lobar pneumonia accompanied by slight fever, back pain and a foul odor from the patient's sputum. Although the patient received broad spectrum antibiotics, pneumonia disseminated to the right lung. A week later, chest computed tomography was conducted which revealed tracheopulmonary-subcutaneous fistula, and a massive subcutaneous abscess with free air production. Drainage from the subcutaneous abscess was done through a chest tube; however, respiratory hypercapnia was not corrected and the patient died. From the culture of drained fluid, anaerobic bacteria including peptostreptococcus sp. were detected. This tracheopulmonary-subcutaneous fistula was thought to be caused by chronic microaspiration of mouth anaerobes, mechanical injury of the trachea under long term ventilator support, and decreased deep back muscle bulk with substitution of adipose tissue around the chest.