Computer-based patient monitoring is a science in transition. Its purposes are vague, its technology variable, and there is no clear evaluation of its utility. Monitoring originally developed because of an intuitive feeling that if we knew more, we would be able to take better care of patients. Physiologic monitoring, statistical monitoring, and integrative monitoring will eventually combine to make a coherent patient care system. However, the subcomponents must be made to work before we reach this stage. It is still unclear what ICU measurements should be monitored and what to compute from those measurements. Once agreed upon, these measurements must be presented in human terms and, ultimately, used to make computer-based diagnosis. The day will come when the computer will be viewed as a tool to extend our medical power to let us take better care of the patient.