BP and heart rate (HR) increase during feeding in neonates. In the current study we investigated the relationship between response magnitude and volume of feeding. Subjects were 14 healthy, medically well, full-term neonates between the ages of 12 and 35 hrs. BP and HR were measured at four times: in the crib prior to feeding, while being held by the mother immediately before feeding, during the first 3 min of bottle feeding, in the crib 20-30 min after feeding. We also measured volume consumed during the first 3 min of feeding. The means (±SE) for systolic BP (mmHg) and HR (bpm) for each of the 4 periods (crib, held, feeding, crib) were: BP of 63±2, 72±2, 80±3, 63±1; HR of 135±4, 136±4, 146±3, 136±3. There were significant increases in BP while being held by the mother (p<.01), and a further increase during feeding (p<.01). HRs were higher during feeding than at all other times (all p<.01). During the first 3 minutes of feeding, the mean formula intake was 19 ml (range 9 to 30 ml). Changes in systolic BP were positively correlated with volume of intake(r=+.75, p<.01). There was no correlation between HR increases and volume of intake. These results show that much of the variability in the BP increases during feeding is related to the amount of nutrient ingested. This could be due to difference in sucking effort or other aspects of feeding efficiency.