Neonates with intrauterine growth restriction (IUGR) are associated with reduced concentrations of IGF-I that might contribute to arterial wall thickening. Direct atherogenic effects of leptin have been described. We aimed to investigate the relationship among abdominal aortic intima-media thickness (aIMT), serum IGF-I, IGF binding protein-3, and leptin levels in neonates with IUGR. Abdominal aIMT was measured in 40 term neonates with IUGR and in 40 controls. Mean aIMT was significantly greater in neonates with IUGR (0.45 +/- 0.03 mm) than in controls (0.39 +/- 0.04 mm, p < 0.0001). Serum IGF-I and leptin levels were lower in neonates with IUGR than in controls. There was a significant positive correlation between aIMT and gestational age, whereas a significant negative correlation was determined between aIMT and IGF-I in the IUGR neonates. For aIMT, significant associations included serum IGF-I level (beta = -0.406, p = 0.006) and gestational age (beta = 0.33 1, p = 0.022) in a multiple stepwise linear regression analysis. In control neonates, serum IGF-I levels were negatively related to aIMT ( beta = -0.750, p < 0.001). Neonates with IUGR have significant aIMT with decreased IGF-I. IGF-I levels determine aIMT not only in neonates with IUGR but also in healthy controls.