Physical examination, clinical laboratory testing, and medical imaging are effective in establishing the presence of liver disease; however, they infrequently establish a definitive diagnosis. Morphologic evaluation of liver tissue is generally accepted as a valuable diagnostic tool in establishing a diagnosis in liver disease. Clinicians have several options for obtaining specimens for morphologic evaluation, including surgically obtained wedge biopsies, percutaneous core biopsies, and fine-needle aspiration specimens. Surgical and core biopsy procedures require anesthesia or sedation and have a substantial risk of bleeding complications. Fine-needle aspiration usually does not require sedation and is rarely associated with hemorrhage; thus, it is frequently chosen for animals that are poor anesthetic risks or have coagulopathies. Diseases like malignant lymphoma, hepatic lipidosis, and suppurative hepatitis are readily diagnosed cytologically, whereas hepatocellular adenomas, hyperplastic nodules, fibrosis, and chronic inflammation are more difficult to identify cytologically.