The diagnosis and prognosis of liver disease is dependent upon an understanding of the biochemistry of hepatic function and its clinical and laboratory manifestations. A complete history and an exhaustive clinical examination are of prime importance to correlate with the indicated laboratory tests. Due to the rapid regenerative ability of the liver, interpretations of all function tests must be viewed only in terms of short time intervals. The use of a few procedures which can be interpreted on the basis of past experience is most desirable.