The pathologic features of acute corrosive esophago-gastritis by ingestion of "Trapunc", a common commercial drain cleansing liquid, is presented. A 37-year-old woman ingested abut 30 ml of Trapunc (3 gm NaOH/100 ml) to commit suicide and received piecemeal esophagectomy and total gastrectomy 9 days after the episode. The esophagus and stomach were extremely friable and necrotic. The most part of the stomach showed acute toxic necrotizing gastritis which was manifested by extensive greenish brown discoloration due to liquefaction necrosis of the mucosa except for a few rugae along the greater curvature. The antrum and distal body revealed severe mucosal detachment and even transmural necrosis. The tissue reaction was basically the same as those of NaOH-induced corrosive esophago-gastritis of acute stage, although it appeared to be severer probably due to sodium hypochlorite, and additive constituent of the ingested cleanser. A unique distribution pattenr of mucosal involvement is discussed.