Liver biology, liver disease and its management present a myriad of challenges to clinicians. Difficulties arise in determining liver functional capacity, which must be effectively measured in a quantitative reproducible manner. Measurement of indocyanine green (ICG) clearance, an exceptional tool that has been used for decades to assess liver function, has traditionally been cumbersome to perform. New technology now allows for rapid and noninvasive determination of ICG clearance making it clinically accessible. This adds ICG clearance measurement to the armamentarium of physiologic monitors that could be routinely used in the evaluation of patients undergoing liver surgery or in the intensive care setting.