Monitoring is an integral part of anesthesia and intensive care management. A wide range of physiological signals and functions are routinely monitored during anesthesia and in the intensive care unit (ICU). The aim of monitoring is to follow the patient’s monitored values, so that any deviations from the “normal” can be detected and effective therapy initiated at the earliest. The monitoring of the future will not be a mere collective display of numbers and waveforms. Monitoring systems will integrate current and trends of physiological data, data from the EMR and use bioinformatics to identify patterns of disease, predict events, determine appropriate therapy and help in prognostication. Intelligent monitoring will help clinicians with decision support, eradicate unnecessary alarms and allow the clinician to focus on the patient. A detailed discussion on the current monitors and their limitations, future trends in monitoring, and the role of the clinician has been given in this chapter.