Impedance respiratory monitoring is not capable of detecting obstructive apneas. We compared a microphone breath sound detector, coupled to the chest wall, with a standard impedance device in 10 sleeping infants and children in order to determine the ability of the breath sound detector to detect normal respirations and central and obstructive apneas. Airflow was used as a standard for all measurements. No difference was found between the breath sound detector and impedance device techniques in the detection rate of either normal respirations or central apneic intervals. There was no statistically significant difference between breath sounds and airflow in the ability of either technique to detect obstructive apnea. The use of a breath sound detector avoids unnecessary stimulation of a sleeping child, whose monitoring would otherwise require that two or three airflow sensing devices be taped on the face. Breath sound monitoring may represent an alternative to impedance and airflow techniques for evaluation of apnea in closely observed infants and children.