We report a case of segmental defect of colonic muscularis propria revealed by perendoscopic perforation in a 64-year-old woman. Segmental absence of intestinal musculature is well documented in new-borns and infants and is more frequent in small bowel. It is characterized by localised absence of muscularis propria without fibrous scar. The remaining layers of the bowel wall are intact. The pathogenesis of this lesion is discussed.