Abstract Aim: To investigate the effect of supplementation with docosahexaenoic acid (DHA) and arachidonic acid (AA) in early neonatal life on cognitive functions among human milk fed very low birth weight infants (<1500 g) at 20 months chronological age. Methods: Randomized, double-blinded, placebo-controlled intervention supplementing human milk with 0.5 mL oil (containing 32 mg DHA and 31 mg AA or placebo) per 100 mL milk from 1 week after birth until discharge from hospital (9 weeks on average). The intervention and control group included 44 and 48 children, respectively. Attention capacity was evaluated by two ‘free-play’ sessions. General cognitive functions were evaluated by the Bayley Mental Development Index (MDI) and an Ages and Stages Questionnaire. Results: The results from the free-play sessions suggested positive effects from supplementation on functions related to attention. Neither the Bayley MDI nor the Ages and Stages Questionnaire showed significant difference between the intervention and control group. Plasma DHA concentration at discharge was positively correlated with both ‘Sustained Attention’ and the Bayley MDI according to chronological age. Conclusion: A positive effect of early supplementation with DHA and AA on 20 months attention capacity was indicated. These findings need further investigation.