We investigated a national cohort of children born extremely immature (<26 weeks gestation, EI) regarding the nature, frequency and severity of the behavioural problems related to the executive functions (EF) and concerning learning skills, from the perspectives of parents and teachers. At 11 years of age 86 of 89 survivors of this cohort were studied and compared with an equal number of controls. Behaviours related to EF, and learning skills were assessed by a validated instrument, namely the Five to Fifteen questionnaire sent by mail to parents and teachers. Compared with controls, parents of EI children reported significantly more problems in behaviours related to EF in all areas assessed (Attention, Hyperactivity/Impulsivity, Hypoactivity, Planning/Organizing, and Working Memory). Teachers' ratings showed a similar pattern. EI children also displayed deficient skills in the 4 standard measures of learning skills. Multivariate analysis revealed that prematurity, gender and behavioural composite score was associated with learning skills. Only a relatively small proportion of EI children (10-30%) exhibited clinically significant impairments. Despite a favourable outcome in many school-age children born at the threshold of viability, these are at increased risk of developing behavioural problems related to EF. ©2013 Foundation Acta Paediatrica. Published by Blackwell Publishing Ltd.