A computerized ICU patient monitoring system is described. The bedside module is a general-purpose unit designed to replace the entire range of traditional monitoring devices. All user-interaction, signal processing, and data presentation in this unit are under the direct control of a microcomputer. The nurse-station module, also containing a microcomputer, is responsible for information routing, controlling nurse-desk equipment as well as data and signal presentation. The system has been in use since 1978 in our 8-bed surgical ICU and since 1980 in an 8-bed coronary care unit. The application programs for ECG, blood pressures, temperature, thermodilution cardiac output, and fluid balance are discussed. The programs for monitoring controlled ventilation are presented in detail. The possibility for feedback control of mechanical ventilation is reviewed. Examples of clinical advantages from automation are given.