A comparative topography and morphometry of the common bile duct and major duodenal papilla was studied on the extrahepatic biliary apparatus of human and major domesticated animals such as horse, ox, Black Bengal (BB) goat, sheep, dog and cat of local breed. In Black Bengal goat, sheep, dog and cat, the extrahepatic biliary system seemed to be the continuation of the cystic duct, which was found to continue as the common hepatic/common bile duct into which all the hepatic/lobar ducts open. In man, the mean length and the mean diameter of the common bile duct were 7.67+/-0.58 cm. and 7.27+/-0.77 mm. respectively. In the ox, these values were 1.57+/-0.72 cm. and 11.82+/-0.79 mm. respectively; in the Black Bengal goat, 7.23+/-0.74 cm. and 4.45+/-0.72 mm. respectively; in the sheep, 5.27+/-0.66 cm. and 3.75+/-0.79 mm. respectively; in the dog, 4.72+/-0.67 cm. and 6.43+/-0.55 mm. respectively and in the cat, 3.26+/-0.87 cm. and 5.63+/-0.43 mm. respectively. In man, the mean length and the mean diameter at the base of the MDP were 4.37+/-0.56 mm. and 3.97+/-0.72 mm. respectively. In horse, these were 52.36+/-0.67 mm. and 12.47+/-0.63 mm. respectively; in ox, 12.53+/-0.73 mm. and 8.83+/-0.68 mm. respectively; in Black Bengal goat, 14.36+/-0.55 mm. and 5.23+/-0.57 mm. respectively; in sheep, 11.27+/-0.69 mm. and 4.51+/-0.74 mm. respectively; in dog, 17.43+/-0.82 mm. and 6.72+/-0.64 mm. respectively and in cat, these values were 12.36+/-0.47 mm. and 7.12+/-0.87 mm. The distance of the Major Duodenal Papilla (MDP) form the pyloric end of the stomach was proportionately shorter in the meat-eaters, i.e., the omnivorous man (9.76+/-0.88 cm), and the carnivores, dog (6.37+/-0.73 cm) and cat (2.75+/-0.87 cm.) when compared to that of the herbivores, i.e., ox (55.37+/-0.68 cm.), BB goat (23.27+/-0.89 cm.) and sheep (25.62+/-0.77 cm.). In the horse, the major duodenal papilla was perpendicular to the duodenal mucosal surface with the largest mean length and the mean diameter. In all other animals, it was obliquely placed on the duodenal surface with its opening directed aborally.