A 48-year-old patient with known alcohol abuse and long-standing liver cirrhosis presented with spontaneous bacterial peritonitis and subsequent hepato-renal syndrome. Autopsy revealed a large hepatocellular carcinoma of the right liver lobe. Histologically, pulmonary arteries, arterioles, and capillaries were occluded by numerous tumor emboli. Small tumor emboli also covered the endocardium of the right ventricle. A review of the literature shows that macroscopic as well as microscopic pulmonary tumor embolism is often diagnosed in patients with a previously unknown malignancy. Moreover, pulmonary tumor embolism radiologically mimics pneumonia, tuberculosis, or interstitial lung disease. Therefore, an autopsy should be considered in cases of fulminant or massive pulmonary embolism to exclude tumor embolism even when the patients' history is insignificant as to this point, and in cases with known malignant tumors and respiratory symptoms to exclude tumor microembolism.