Digital computers have become valuable assistants in the intensive care units of many American hospitals. Computerized patient monitoring systems offer the potential for improved patient care by aiding in the early identification of trends in monitored physiologic para- meters and by relieving the medical staff of many of the repetitive clerical tasks which occupy their time. Advanced monitoring systems further assist by initiating blood replacement and drug infusions under carefully controlled conditions. Consideration of several operational systems in the United States supports these concepts. A state-of-the- art intensive care unit monitoring system, currently being implemented at the National Institutes of Health, is described in depth.