We report three cases of pneumatosis cystoides intestinalis (PCI) occurring in association with post-surgical bowel anastomosis. A 74-year-old man, a 58-year-old woman, and a 62-year-old woman were found to have PCI at the colonic side of a bowel anastomosis at 4 years, 3 years and 1 year after operation, respectively, for right colon carcinoma, although all were asymptomatic. They all had a positive anti-nuclear antibody test and had received postoperative cancer chemotherapy. The clinical features of 123 cases of PCI reported in Japan between 1981 and 1995 were also reviewed. On the basis of the present and previous cases, we propose that post-surgical anastomosis, cancer chemotherapy, and predisposition to collagen vascular disease might be responsible for the damage to intestinal mucosa that leads to the development of PCI.