Although there is a strong rationale to supplement gravid patients suffering intrauterine growth restriction (IUGR) or preeclampsia with Arginine or other nitric oxide donors, evidence in the literature has been inconclusive. The current study was designed to determine whether oral treatment with L-Arginine, a nitric oxide (NO) donor, would enhance birth weight and/or decrease neonatal morbidity in pregnancies with severe vascular intrauterine growth restriction (IUGR).