Liver biopsy is a very useful way of assessing copper status in cattle, as well as for other diagnostic uses such as assessing liver fat concentration. In the past, rather large liver specimens were required for copper determination. The analytical equipment available today allows us to accurately measure copper and other mineral concentrations on very small liver samples. These samples can be taken quickly, conveniently, and with little or no risk to the animal. The liver biopsy procedure is very safe, and no complications have been observed in hundreds of samplings. However, there is some small potential of inducing necrotic hepatitis, so if the animals have not been vaccinated against clostridial diseases, it is probably wise to administer an injection of penicillin or similar antibiotic at the time of sampling.