Here we describe a premature male infant who was accidentally given 10 mL of expressed breast milk intravenously over a 3.5-hour period. Having survived this event with supportive care, this boy was attending regular school with no obvious neurologic or learning difficulties at 6 years of age. In 1998, after a query on an e-mail discussion group for health care providers in neonatology (NICU-net), we were informed of 8 similar events that proved fatal in 3 infants. A root-cause analysis revealed that accidental intravenous administration of breast milk or formula can be avoided by the use of color-coded enteral-administration sets with Luer connections that are not compatible with intravenous cannulas. The addition of methylene blue to feeds, or bolus enteral feeds (instead of continuous gastric feedings), may also help prevent such errors. These cases show the value of gathering information about rare but important events through a neonatal network. In addition, they confirm that prevention of medical error should focus on faulty systems rather than faulty people.