The incidence of critical isthmic coarctation among preterm infants with a birth weight less than 750 g is expected to be fewer than 1:2,000,000 live births. A male twin was born after 26 weeks of gestation with a birth weight of 545 g. On day 9 of his life, he experienced anuria due to a critical neonatal isthmic coarctation. Resection of the coarctation and end-to-end anastomosis were performed. A magnetic resonance imaging (MRI) scan when the boy was 2 years old demonstrated no significant postoperative re-stenosis. At this writing, up to the age of 6 years, the boy has not needed retreatment. Critical neonatal isthmic coarctation in extremely low-birth-weight preterm infants can be corrected successfully.