In the article “3-Cholorotyrosine as a Marker of Protein Damage by Myeloperoxidase in Traceal Aspirates from Preterm Infants: Association with Adverse Respiratory Outcome” (Pediatr Res 53:455–462), the units for chlorotyrosine in Tables 2 and 3 should be millimoles instead of micromoles per mole tyrosine. The values in the tables are 1000-fold less than those in the text and figures, which are in micromoles per mole tyrosine. The authors regret the error.