A 4.3-y-old, colony-bred female baboon (Papio hamadryas anubis) of low social rank and exhibiting no clinically significant signs of illness or distress was found dead at the Oklahoma University Health Sciences Center baboon breeding facility at El Reno, OK. Prior to death she exhibited excessive grooming behavior both toward herself and other baboons. In addition, she was consistently shy, timid, reclusive, and prone to minimal sustained movement (that is, generally lethargic behavior). Animals of low social rank typically exhibit some degree of these behaviors in order to avoid surplus interactions with other animals within their groups, which can lead to conflict and injury. Accordingly, her death was surprising in view of the apparent lack of clinical signs. Necropsy established the cause for death as systemic shock with resultant cardiovascular collapse resulting from a massive jejunal intussusception. This intussusception and resulting entrapment of the jejunal mesenteric vasculature caused total occlusion of the small bowel blood supply, with resulting hemorrhage and ischemic necrosis (small bowel infarction). Jejunal intussusceptions generally are considered to be uncommon and therefore are rarely reported in either the veterinary or human literature. Of special interest was the cause for this intussusception, determined to have been a large hairball located at the most proximal portion of the jejunum. Extending from this hairball and traversing essentially the entire length of the jejunum was a braided strand of hair acting as a string foreign body about which the intussusception formed. In light of our findings we suggest that animals of low social rank exhibiting excessive grooming behavior and lethargy might merit clinical evaluation to rule out possible abdominal disorders.