Variant patterns of peritoneal folds could be formed due to the complex nature of the embryology of the peritoneum and the gastrointestinal tract. When uncommon peritoneal folds are formed, they could influence aberrant formation of surrounding gastrointestinal structures and create spaces that may harbour peritoneal fluids in cases of infection or malignant tumor. One of such variant peritoneal folds is the cystoduodenal ligament which is a doubled peritoneal membrane attaching the gallbladder to the duodenum. Yet no study was found that had reported the frequency of occurrence of the cystoduodenal ligament. The current study determined the prevalence of the cystoduodenal ligament in forty adult cadavers. The ligament was reported in 35% of cases. The ligament was further classified as types I and II. Type I cystoduodenal ligament was attached partially to the gallbladder (neck and proximal part of body) while type II was attached to the entire extent of the gallbladder. Type I occurrence was found in 44% and type II was found in 56% of the occasions of cystoduodenal ligament formation. It is concluded that the cystoduodenal ligament could be commonly found, it possesses important vascular structures, and it could affect the shape of the gallbladder. Surgeons, radiologists, and anatomists should be kept abreast of these findings.