A detailed evaluation of the involvement of regional lymph nodes in 33 patients with cancer in the pancreas, distal common bile duct and papilla of Vater was undertaken with the aim of delineating the patterns of lymphatic spread of the tumor. Regional lymph nodes were involved in 91.7% of patients with pancreatic carcinoma, 62.5% of those with carcinoma of the distal common bile duct, and 58.3% of those with carcinoma of the papilla of Vater. The neck of the pancreas appeared to be an "entrepot" through which cancer cells pass on their way to the lymph nodes. Other outstanding routes of spread include a route via the nodes situated around the superior mesenteric artery, a perineural route passing through the pancreatic plexus, and metastasis to the nodes along the abdominal aorta. Grouping of the involved lymph nodes is discussed and a new grouping is proposed with reference to the literature.