The pancreatoduodenal groove is a potential space bordered by the head of the pancreas, duodenum, and common bile duct [1-3] (Fig. 1). Diseases arising from or involving the pancreatoduodenal groove can be categorized into four types: diseases associated with the pancreas, duodenum, lymph nodes, and distal common bile duct. We present the key diagnostic findings of these diseases, along with features that can be used to distinguish among them, in this pictorial essay. Knowledge of the features of each disease may allow one to make a specific diagnosis, which assists in clinical management and helps to prevent unnecessary surgical intervention.