The techniques for cannulation of peripheral arteries have been well described in articles on neonatal care.1,2 Most centers currently utilize this technique when umbilical arterial catheterization has failed, when a complication of umbilical artery catheterization has occurred, or when umbilical access is limited because the neonate is older. Occasionally, as reported in this issue of AJDC by Randel et al,3 cannulation of a peripheral artery is selected as an alternative to umbilical artery catheterization for sampling arterial blood and monitor-ing blood pressure. They selected less ill, larger premature and term infants for this procedure. This was likely not just due to the technical difficulties imposed by the size of tiny premature infants. Peripheral arterial cannulas are not complete alternatives to umbilical catheters. Infusion of fluids, glucose, electrolytes, and drugs that are usually administered via the umbilical catheter requires placement and maintenance of an intravenous line. This requirement can