Liver tumors are rarely found in domestic animals. Majority of liver tumors are actually metastatic tumors, but primary liver tumors that can be found include: hepatocelullar carcinoma, hepatocelullar adenoma, hepatoblastoma, cholangiocelullar carcinoma, cholangiocelullar adenoma, adenomas and carcinomas of the gallbladder, carcinoids and primary mesenchymal tumors (fibrosarcoma, leiomyosarcoma, osteosarcoma, hemangioma and hemangiosarcoma). 170 samples of liver biopsies were examined to determine the incidence rate of primary liver tumors in domestic animals. Incidence rate of primary liver tumors was 22% (37/170), metastatic tumors 29% (49/170) and non-tumorous growths 49% (84/170). The most commonly diagnosed tumor was hepatocellular carcinoma (51%), followed by cholangiocelullar carcinoma (19%), primary hemangiosarcoma (14%), hepatocelullar adenoma (11%) and primary sarcomas (5%). Malignant tumors are more common than benign in dogs which was confirmed with hepatocelullar carcinoma being the most common tumor found in dogs followed by cholangiocelullar carcinoma. However, the incidente rate for metastatic tumors was much greater than the one of primary tumors. Tumors that metastasized the most in the liver were: hemangiosarcoma of the spleen and the heart, pancreatic adenocarcinoma and lymphoma. There is no breed or sex predisposition for developing primary liver tumors and hyperadrenocorticism has not been identified as a risk factor. However, it has been confirmed that there is an increased risk of developing liver tumors in animals over the age of 10.