Currently, there is an unprecedented interest in acid-base problems and several new approaches have been recommended.1-4 However, the only serious challenge to the supremacy long enjoyed by the traditional methods is offered by the system of Astrup and his associates.2-5 For a complete review of this controversy the reader is referred to the recent symposium sponsored by the New York Academy of Science.6 It should be emphasized that either the Astrup system or the traditional approach can be used with excellent results if the clinician is experienced with the method in question and understands the pathophysiology of the disease state with which he is dealing. Equal emphasis should be placed on the truism that in order to evaluate an acid-base disorder by either approach, one must be familiar with the compensatory changes which occur as the result of a given primary disturbance. A common misconception is that