Polycythemia associated with hepatic carcinoma was diagnosed in a 10-year-old cow, an 8-month-old heifer and a 3-year-old sheep. The cow was referred to our clinic because of weight loss, reduced appetite, hematuria, marked reddening of the mucosa of the tear canal, oral cavity and vestibule and an increased hematocrit. Clinical examination also revealed injected scleral vessels. The erythrocyte count, the PCV, hemoglobin concentration and the activities of the hepatic enzymes were increased. Ultrasonographic examination revealed a very large liver with a focal echogenic lesion. Based on all findings, a diagnosis of polycythemia associated with a liver tumor, was made. The cow was slaughtered. Multifocal liver tumors were diagnosed histologically as hepatocellular carcinoma. The heifer and sheep had similar clinical and hematological findings. Hepatocellular carcinoma was diagnosed in the heifer and cholangiocellular carcinoma in the sheep. It was concluded that in all three patients, polycythemia was caused by hepatic carcinoma.