The results of blood and imaging tests are non-specific in liver disease, so a liver biopsy is usually indicated to give a diagnosis and allow most effective treatment. Certainly, steroids or copper chelators should never be used without justification from a liver biopsy. The clinician must decide the best way to perform this biopsy considering how stable the patient is, the financial resources of the owner and the relative reliability of the results obtained with different methods. There is also little point in taking a biopsy which is not representative of the underlying disease – if the sample is too small, or from the wrong place, or only from one of a number of organs affected with disease, it may lead to the wrong conclusions being drawn and the wrong, or incomplete, treatment protocols. Fine needle aspiration (FNA) cytology is not strictly a biopsy but a potential alternative to more invasive biopsies but beware becoming ‘liver FNA happy’ for fear of false diagnoses and wasting the client’s money. FNAs are only helpful in a small number of cases, predominantly for bile aspirates and to rule out feline hepatic lipidosis or lymphoma. Wedge biopsies taken at laparotomy or laparoscopy are the most reliable diagnostically.