OBJECTIVE: Nasal continuous positive airway pressure (nCPAP) has been shown to improve the outcome of infants with respiratory distress syndrome. However, noise generation could be of concern. Therefore, our study was designed to measure the noise levels of various CPAP drivers. DESIGN: For infants admitted to our neonatal intensive care unit and paediatric critical care unit, we measured the noise level in the oral cavity, using a microphonic probe with a flexible capillary tube. Various CPAP drivers and interfaces have been tested. RESULTS: 27 measurements were made in eight infants. Mean noise level was 88.6 (SD 18.8) dB and was correlated with flow (p<0.01) but not with pressure. A noise level above 90 dB was detected in 67% of the measurements. CONCLUSIONS: nCPAP drivers are valuable devices for neonatal care that may prevent primary mechanical ventilation or re-intubation, but generate a large amount of noise, often higher than occupational limits accepted for adult workers. Therefore, new devices must be designed to minimise this possible noxious exposure of premature infants to unacceptably high noise levels.