A 42-year-old man with alcoholic liver cirrhosis was admitted for the treatment of his esophageal varices. Following the endoscopic injection sclerotherapy, esophageal varices disappeared immediately, but thrombocytes were also rapidly reduced. Immunological examinations, including antiplatelet antibody test and lymphocyte transformation test to administrated agents revealed no abnormality. Sonography showed marked increase of spleen size, and portography demonstrated interception of injected esophageal varices and tortuous dilatation of splenic vein. We could conclude, on the basis of radiological and immunological findings, that, in our case, this procedure could intercept the blood flow of injected varices, important collateral circulations of the portovenous system, but it induced, on the other hand, rapid increase of splenic vein pressure and marked decrease of thrombocytes due to splenic hyperfunction.