A large focus of cystic intestinal pneumatosis appeared as an accidental finding in a 59-year-old man suffering from obstructive lung disease, with cor pulmonale as the cause of death. The gas pseudocysts were found in the submucosa, muscularis propria and in the subserosal space. The pseudocysts were lined by flattened cells of connective tissue origin with presence of occasional macrophages. We believe that the lesion started by focal damage of the mucosal membrane, which was followed by penetration of stool particles with microbes into the submucosa. E. coli and Morganella morgani are the probable producers of the gas bullets.