A thermal imaging system developed by Plessey Research, which is based on a pyroelectric linear array sensor, has been used to carry out surveillance of severely burned patients in an intensive care unit. Images are produced in 16 colours by a modified BBC microcomputer. Software has been developed to alow simultaneous display of the image and patient information using a multi-mode screen. Body heat losses can be calculated from the temperature data, coupled with information on room temperature, humidity and other environmental variables. The camera is mounted in the ceiling of the intensive care room so that images can be recorded automatically at regular intervals. The information provided by this system will be used in adjusting the treatment conditions to maintain the delicate energy balance.