Selected cases showing rare variations of the arteries of the upper abdomen indicate how difficult the exact identification of individual vessels can be. In the presence of such variations, which usually involve several vessels, it is essential to find and demonstrate all vessels in the upper abdomen. Vessels which are not seen easily must also be specially searched for. In the presence of anomalous vessels, angiography may prevent the surgeon from ligating the incorrect arteries during operation on the pancreas, the liver, stomach, spleen or colon.