The growth hormone response to a single intravenous dose of human growth hormone-releasing hormone (GHRH) was examined in 23 healthy neonates (12 term and 11 preterm) aged 2–4 days. There were no significant increases in growth hormone concentrations at any point in time studied following GHRH administration in either group of new-borns. The mean basal growth hormone levels of term neonates were significantly higher than those of the premature newborns (39.6 ± 5.3 vs. 23.2 ± 3.3 ng/ml; p < 0.01) and this difference in growth hormone remained significant 15 and 30 min after GHRH injection. Gestational age correlated positively with both basal and peak growth hormone concentrations in our patients. In conclusion, first, neonates studied in their first days of life have high basal levels of growth hormone and fail to further secrete any significant amount of growth hormone following a single dose of GHRH, and, second, premature newborns secrete significantly less growth hormone than do term neonates.