We prospectively studied the vagal response to feeding tube insertion in eight healthy preterm infants, on three occasions in each infant during the first three weeks of life. Heart rate, oxygen saturation, respiration and cerebral blood flow velocities were assessed before, during and immediately after insertion of an orogastric feeding tube. The whole procedure was recorded on video. The duration and quality of tube insertion and the behaviour of the infant were evaluated from the recordings. Twenty-one measurements in eight infants were evaluated. The heart-rate decrease observed immediately after tube insertion correlated significantly with the duration of tube insertion, the quicker the manipulation, the greater the heart-rate decrease (P = 0.000). The maximal decrease of oxygen saturation after tube insertion correlated with the degree of heart rate deceleration (P = 0.009). Significant alterations of the flow velocities were observed only when the heart rate fell below 80 beats/min. We speculate that such episodes of bradycardia can be avoided by carefully inserting the feeding tube over a period of at least 15 s.