A portable microprocessor-based noninvasive cardiopulmonary heart rate monitor is described for use in situations in which direct contact with the subject is either impossible or undesirable. Low-power Doppler microwaves are employed to measure the chest movements associated with the expansion and contraction of the heart and the lung. After proper analogue signal conditioning, the signal is digitised and processed by an Intel-85 microprocessor system. Pattern-recognition techniques are applied to extract the heart and respiration rates. The algorithm is tested on anaesthetised rats. The system has also been tested on a limited number of human subjects. Results indicate that the meter can detect the desired physiological signals, with good accuracy, of a standing or supine human subject wearing ordinary clothing.