A novel case report of acute abdominal compartment syndrome (ACS) with respiratory and hemodynamic collapse during colonoscopy in a western lowland gorilla (Gorilla gorilla gorilla), notably, without colonic perforation is presented here. ACS is a rapidly progressive and sustained increase in intra-abdominal pressure leading to shock with multisystem organ failure. Surgical intervention was mandatory, and abdominal decompression was immediately life-saving, although the patient died 1 wk later of surgical complications. Colonoscopy is a widely performed procedure that is generally considered safe, and serious complications during colonoscopy are rare. ACS has been previously reported during colonoscopy with perforation in four cases (human)1,4,6,8. In this instance there was no evidence of perforation, representing not only a rare complication of the procedure, but also a novel cause of ACS. This is the first report of ACS in a nonhuman primate and of nonperforation-associated ACS in human or nonhuman primates.