ObjectiveTo determine the impact of one probiotics combination on the neurodevelopment of very preterm children at 2–5 years corrected gestational age (CA).DesignFollow-up study of survivors of a double-blinded, placebo-controlled, randomised trial of probiotic effects on late-onset sepsis in very preterm infants that found reduced necrotising enterocolitis.Setting10 tertiary perinatal centres in Australia and New Zealand.Patients1099 very preterm infants born <32 weeks’ gestation and weighing <1500 g.InterventionProbiotics (Bifidobacterium infantis, Streptococcus thermophilus and Bifidobacterium lactis) or placebo administered from birth until discharge home or term CA, whichever came sooner.Main outcome measuresMajor neurodevelopmental impairment comprised any of moderate/severe cerebral palsy (Gross Motor Function Classification System score 2–5), motor impairment (Bayley-III Motor Composite Scale <–2SD or Movement Assessment Battery for Children <15th centile if >42 months’ CA), cognitive impairment (Bayley-III Composite Cognitive or Language Scales <–2SD or Wechsler Preschool and Primary Scale of Intelligence Full Scale Intelligence Quotient <–2SD if >42 months’ CA), blindness or deafness.ResultsOutcome data were available for 735 (67%) participants, with 71 deaths and 664/1028 survivors assessed at a mean age of 30 months. Survival free of major neurodevelopmental impairment was comparable between groups (probiotics 281 (75.3%) vs placebo 271 (74.9%); relative risk 1.01 (95% CI 0.93 to 1.09)). Rates of deafness were lower in probiotic-treated children (0.6% vs 3.4%).ConclusionAdministration of the probiotics combination Bifidobacterium infantis, Streptococcus thermophilus and Bifidobacterium lactis to very preterm babies from soon after birth until discharge home or term CA did not adversely affect neurodevelopment or behaviour in early childhood.Trial registration numberAustralia and New Zealand Clinical Trials Register (ANZCTR): ACTRN012607000144415.