Acupuncture is one of the most popular complementary therapies in the world. Pneumothorax due to perforation of the lungs by needle insertion is one of the most common and serious complications of acupuncture treatment. Although there have been several case studies of pneumothorax induced by acupuncture, as far as we know there have been no reports on the pathological findings of autopsy cases. In this report, we describe the pathological findings of an autopsy case of bilateral tension pneumothorax after acupuncture. The patient suffered dyspnea and chest pain soon the completion of an acupuncture treatment, and died 90 min later. Several ecchymoses were macroscopically observed on the parietal pleura in the left and right thoracic cavity, suggesting that needles were inserted into the thoracic cavity and that the lungs were perforated. The many black spots we observed on the parietal pleura along the vertebral column microscopically consisted of a number of dust-like black pigments and macrophages containing these pigments. These spots seemed to have appeared because of the previous insertion of needles.