BACKGROUND: Although early life growth pattern is associated with cardiovascular disease later in life, it is unknown whether vascular changes associated with excess early weight gain already occur in early childhood. METHODS: In the Wheezing-Illnesses-Study-Leidsche-Rijn (WHISTLER) birth cohort, weight and height from birth to 3 months of age were used to calculate Z-scores of individual weight and length gain rates. In the first 333 children who turned 5 years old, intima-media thickness, distensibility, and elastic modulus of the carotid artery were measured ultrasonographically. The association between weight gain rate for length gain rate (WLG), as a measure of excess weight gain, and vascular characteristics was assessed by generalized linear modeling. Interaction between birth size and WLG was tested. RESULTS: Per 1 SD increase in WLG, carotid intima-media thickness was 5.1 μm (95% confidence interval, 1.0-9.2; P value = .01) higher (adjusted for age, gender, current height, and observer). The thinner the children were at birth, the stiffer the arteries were with increasing WLG (interaction between birth size and WLG-distensibility: P = .04; elastic modulus: P = .03). CONCLUSION: Excess early postnatal weight gain leads to vascular changes already in early childhood, characterized by thicker arterial walls. In children who are relatively thin at birth, excess early postnatal weight gain also leads to stiffer arteries. This supports the view that cardiovascular disease risk is associated with growth pattern early in life.