BACKGROUND: Very low birth weight (VLBW, birth weight<1500g) children have increased risk of behavioral problems. Diffusion tensor imaging (DTI) of the brain shows reduced white matter maturation. Long-chain polyunsaturated fatty acids are hypothesized to improve both myelination and behavioral outcome. AIMS: To test the hypothesis that postnatal supplementation with docosahexaenoic acid (DHA) and arachidonic acid (AA) to very low birth weight infants would influence cerebral white matter measured by DTI and improve behavioral outcome at 8years of age. STUDY DESIGN: Eight-year follow-up of a randomized, double-blinded, placebo-controlled study of postnatal supplementation with DHA and AA to 129 VLBW infants fed human milk. SUBJECTS: Ninety-eight children (76%) met for follow-up at 8years. OUTCOME MEASURES: Cerebral white matter measured by DTI. Behavioral outcome measured by Strengths and Difficulties questionnaire and selected scales from the Child Behavior Checklist. RESULTS: No significant differences between the intervention group and the control group were found on white matter microstructure or behavioral data. A non-significant finding of higher fractional anisotropy (FA) in a cluster in the corpus callosum of the intervention group is discussed. CONCLUSIONS: The present study is the first long-term follow-up of a randomized controlled trial with DHA and AA to human milk fed VLBW infants exploring cerebral white matter microstructure measured by DTI and parent-reported behavioral problems. No effects on white matter microstructure or behavioral outcome were observed at 8years of age.