Impedance pneumography is potentially a non-invasive method of measuring infant tidal volumes. In order to evaluate the accuracy of impedance pneumography, eight healthy infants (weighing from 709 to 3506 grams) were randomly chosen and studied. Simultaneous measurements of tidal volumes were made by calibrated spirometry and by transthoracic impedance pneumography. The results were statistically compared. Transthoracic impedance pneumography provided a reliable estimate of tidal and minute volumes in these newborn infants.