Background: Intrauterine exposure to alcohol may affect cardiovascular development, increasing risk of cardiovascular malformations. Intrauterine exposure to light maternal alcohol intake has been reported to affect human umbilical arterial contractility, and adult sheep exposed in utero have had altered cerebrovascular reactivity. In human adults, alcohol intake affects arterial stiffness. Objectives: We investigated whether intrauterine exposure to alcohol was associated with childhood pulse wave velocity (PWV), a measure of arterial stiffness. Methods: On postnatal day 4, mothers of 147 twin pairs born in Tasmania from 1991 to 1993 reported alcohol intake during each trimester of pregnancy. At 9 years, child PWV was assessed over carotid-femoral and femoral-dorsalis pedis arterial segments by applanation tonometry. Results: Carotid-femoral PWV was 0.2 m/s (95 CI 0.06, 0.4) higher (indicating stiffer vessels) in children whose mothers drank alcohol in the 2nd trimester rather than abstained, after adjusting for potential confounding factors. A similar effect was not seen for femoral-dorsalis pedis PWV. Findings were independent of child blood pressure which correlated strongly with PWV. Alcohol intake varied little between trimesters, so it was not possible to assess the effect of timing of exposure. Conclusions: Carotid-femoral PWV in adults is predictive of cardiovascular morbidity and mortality. The degree of continuity between childhood and adulthood PWV is unknown, but as we found an association between prenatal alcohol exposure and carotid-femoral PWV at 9 years, a permanent change in vessel wall structure or function is possible. These findings need to be confirmed in other and larger cohorts, and mechanistic animal studies are needed.