Abstract
A cursory evaluation of the Acute Physiology and Chronic Health Evaluation, commonly known as the APACHE scoring system, validates its relevancy as the most widely used method for assessing severity and prognosis in intensive care unit patients. The APACHE system works and the evolution from APACHE I to APACHE IV reveal that each version has its positives and negatives. It would behoove critical care nurses to know differences and how each could be best utilized.