The most common cause of occlusion of the splenic vein is pancreatic disease, such as pancreatitis or carcinoma of the pancreas. As compared with benign causes, carcinoma of the pancreatic body or tail may readily involve not only the splenic vein, but also, eventually, the splenic artery. Therefore, the clinical features of occlusion of the splenic vein may be profoundly altered according to the nature of the underlying causes. In an attempt to clarify the pathophysiologic findings and hemodynamic mechanism of occlusion of the splenic vein associated with carcinoma of the pancreas, three patient reports were selected from our past experience. Upon analyzing the clinical course of these patients, three consecutive phases may be distinguished. Phase 1 is the insidious or latent phase represented by Patient No. 1. The splenic vein is partially occluded and gastric varices or splenomegaly has not developed. Phase 2, the collateral developing phase, is represented by Patient No. 2. The splenic vein is completely occluded while the splenic artery is patent, resulting in marked gastric varices and splenomegaly. Phase 3 is the vanishing phase and is represented by Patient No. 3. The occlusion of the splenic artery is superimposed on the occlusion of the splenic vein, causing gastric varices to vanish and the enlarged spleen to shrink.