Three dead tigers were dissected and representative samples from the gastric mucosa, duodenum and livers were taken for histopathology and transmission electron microscope for further investigation of the cause of death. Post-mortum examination showed accumulation of straw in the stomach outlet (Phytobezoar), together with pronounced ulcers, which was surrounded by hemorrhagic zones. Light microscopy showed loss of the gastric mucosal epithelium, necrosis of the gastric glands, hyperemia of the submucosal blood vessels, and lymphocytic and few neutrophils in the submucosa. These changes indicated acute-subacute gastritis. Subcapsular hepatocellular necrosis expressed by hepatocellular lysis, pyknosis and karyorhexis of the hepatocytes nuclei were also observed. Transmission electron microscopical observations showed the presence of intercellular, and interacellular elongated, coiled, and spiral form of Hellicobacter bacteria in close contact with the gastric glandular epithelium. Moreover, rounded-shaped bacteria were observed in association with the helicobacter bacteria. The duodenum revealed also the presence of both types of bacteria. These results suggest mixed infection with the complication of Phytobezoar which cause obliteration of the stomach outlet with chronic constipation and fever, might be responsible for the death of tiger.