Spontaneous ventral hernia through the rectus abdominis sheath is perhaps the rarest hernia, with eight previously reported cases since 1937. The condition has not been reflected in the popular treatises on hernia. An 83-year-old male patient underwent surgery for intestinal obstruction. A spontaneous Richter's hernia of the small intestine through the posterior rectus abdominis sheath was successfully treated with bowel resection and tissue repair. Hernias of this variety are not well known and thus are rarely suspected. Their successful management is based on accurate emergency diagnosis and surgery, which we recommend as the best chance for a successful outcome.