Since a comprehensive discussion of liver function tests would require much more time than is available in this symposium, this article is limited to a presentation of the indications for doing the tests, of specific recommendations of the most satisfactory technics of certain principles and limitations in their interpretation and of references to the most recent authoritative literature. Those interested in a more detailed discussion may consult several excellent recent reviews. 1 From the point of view of an internist teaching both physical and laboratory diagnosis, I want to emphasize that liver function tests, in fact all laboratory tests, are a valuable supplement to but no substitute for a well taken history and a thorough physical examination. The intelligent interpretation of the tests depends on an understanding of the underlying physiologic principles as outlined in the preceding discussion, 2 of the common sources of error in the methods 3 and