Blood pressure, heart rate, and oxygen saturation were monitored prospectively during 40 echocardiography recordings on 17 preterm infants (25-29 weeks; 510-1430 g), to examine whether echocardiography can be performed without disturbing cardiorespiratory status in preterm infants. There was no impact on absolute blood pressure. Heart rate increased by a mean of 4 beats per minute, and oxygen saturation decreased by a mean of 1% during echocardiography. While these changes reached statistical significance they are not of clinical significance as they remained well within ranges seen during control rest periods. All readings had greater minute-to-minute variability during echocardiography but differences were small and again remained within physiological ranges.