The monitoring of the development of respiratory function in low-birth-weight or sick neonates is important in its overall treatment. The most direct approach to obtaining information on respiratory function is to monitor the activity of the diaphragmatic muscular system rather than measure the resultant change in lung volume or ventilator output, which cannot be guaranteed to be directly related to the neonate's own respiratory activity. The system was designed to assess the feasibility of monitoring respiratory activity in such neonates by measuring the diaphragmatic electromyograph. It is hoped that this system can be used to monitor the development of lung function and possibly, if reliability proves adequate, the synchronisation and control of ventilator assistance. To monitor the EMG, the dominant effect of the ECG was removed using a digital processor. Initial clinical measurements indicate that neonatal respiratory activity can be monitored by measuring the diaphragmatic EMG. Comparative measurements show the EMG method is faster in detecting the inspiratory phase of a breath. Measurements on ventilated neonates showed the presence of intermittent respiratory activity. It also is proposed that clinically relevant information may be deduced from the analysis of the morphology of the detected EMG waveform.