Aim: Although exclusive breastfeeding is recommended for all newborn in the first 6 months of life, only 13% of Danish premature infants complies with this. This trial aimed to examine whether oral stimulation prolonged exclusive breastfeeding in premature infants. Method: A randomised controlled trial was conducted at the Neonatal Intensive Care Unit, Hvidovre Hospital, Denmark between 2016 and 2018. Systematic oral stimulation was performed by the parents after training by occupational therapists. Primary outcome was exclusive breastfeeding duration with 6 months' follow-up, analysed by intention-to-treat. Results: Included were 211 infants (53% boys) with a mean gestational age of 231 days, allocated in ratio 1:1 to oral stimulation or standard care. There was no difference in exclusive breastfeeding duration between infants orally stimulated and control infants. Thus, for orally stimulated infants, median duration was 122 days (interquartile range 40-183) in contrast to 154 days (interquartile range 61-183) for the controls, P value.16. At 6 months of age, 27% of orally stimulated infants were exclusively breastfed compared with 25% of controls. Conclusion: In healthy premature infants, oral stimulation performed by parents has no long-lasting effect on breastfeeding duration. Attention should be directed to parental education and involvement.