Background: The insertion/deletion polymorphism of the angiotensin-converting enzyme (ACE-ins/del) and the angiotensin II type 1 receptor 1166A/C polymorphism (ATR1166A/C) were reported to be associated with several unfavorable outcome parameters in preterm infants like bronchopulmonary dysplasia, persistent ductus arteriosus and impaired insulin sensitivity. Objective: To confirm the above-mentioned associations in a large cohort of very-low-birthweight (VLBW) infants. Method: Clinical data of VLBW infants were prospectively recorded. The ACE-ins/del polymorphism and the ATR1166A/C polymorphism were determined by polymerase chain reaction in 1,209 and 1,168 infants, respectively. Results: There was no significant association between ACE-ins/del or ATR1166A/C genotype and outcome parameters (death, intraventricular hemorrhage, sepsis, bronchopulmonary dysplasia, ventilation, supplemental oxygen at discharge, postnatal treatment with insulin, surgery for intestinal perforation/necrotizing enterocolitis/retinopathy of prematurity/persistent ductus arteriosus. Conclusion: Both known functional polymorphisms of the renin-angiotensin system do not seem to be associated with the outcome of VLBW infants.