On October, 1971, a 4-month-old male Himalayan cat died of feline infectious peritonitis after suffering rom severe ascites, dyspnea, and anorexia for 11 days Congenital pericardiac diaphragmatic hernia was evealed by postmortem examination. The hernial ontents in the pericardiac space, were malformed hepatic tissue having developed from the left medial lobe of the liver. Fibrous inflammatory lesions were recognized on the serous membrane. The pericardium was enlarged by the hernial contents. The heart was compressed leftward and twisted.