PURPOSE: The study was done to explore growth variation in head circumference (HC) in extremely premature infants (EPI) with brain injury. METHODS: A retrospective cohort study was conducted with 79 cohort samples from the archives of the catch-up growth project. Mean age of the infants was 29.2 weeks of gestation and mean HC, 27.1 cm at birth. Their HC measurements were retrieved from the archives up to 6 month of corrected age (CA) and analyzed against history of brain injury during hospitalization. RESULTS: Overall growth retardation in HC was observed in the cohort sample compared to longer gestation premature infants. EPI with brain injury showed decreased HC compared to infants without brain injury, and resulting growth variation across 6 month of CA. Highest retardation in HC growth was observed in male infants with brain injury. CONCLUSION: Extreme preterm birth itself may function as a major obstacle against HC growth toward term age in EPI. Sustainability of brain injury could be observed with higher HC growth retardation after term. Evolutionary favor to female infants may exist in HC growth of EPI. Intensive education on HC monitoring is highly suggested for parents of EPI, particularly with children with brain injury.