This book is the result of several years of enthusiastic planning and effort. Much of this enthusiasm came from the experience of devel{)ping Critical Care Consultant, a large BASIC program for critical care applications (St. Louis, C. V. Mosby, 1985). Working with clinicians showed me that many were interested in learning about clinical applications of computers (and even programming in small doses) but were faced with a paucity of clinical application software. Few had the time or training to develop any such software on their own. After a search through the existing medical literature unearthed relatively little in the way of usable programs, I decided that a series of small clinical applications programs would be of use to the medical community. At the onset a number of strategic decisions were made: (1) the programs would be written in BASIC, in view of its universal popularity, (2) the units used for clinical laboratory tests would be those in common use in the United States, (3) the programs would be simple and easily understood and employ no exotic tricks that were not easily transported across computers, (4) references to the literature would be provided to allow the clinician to critically assess the algorithm or method used himself or to follow up on subsequent criticisms that may have been published, and (5) the programs would demonstrate reasonable standards of software engineering in terms of clarity, trans portability, documentation, and ease of modification.