Despite extensive research and a multitude of computer systems, there is no viable computerized system that is even remotely capable of approaching the skill of an expert human physician. Minor obstacles in the design of a practical system include imprecise medical terminology, the use of nonindependent clinical parameters, incorrect or inaccurate information supplied to the computer, and static representation of a patient's medical history. Major problems that go beyond computer manipulation of data include the requirement for a massive data base, representation of medical knowledge in general rather than specific terms, and physician fallibility in the design of a computer system.