This document provides information about arterial blood gas (ABG) interpretation including: 1) Normal ABG values and implications of abnormal values in assessing lung, heart, kidney and metabolic function. 2) Techniques for collecting ABG samples and common errors. 3) A step-wise approach to diagnosing acid-base disorders by determining if the primary disturbance is respiratory or metabolic and the severity. 4) Descriptions and interpretations of several case studies involving patients with respiratory and metabolic acid-base abnormalities.