The behaviour problems of children born preterm at school age are well known, but there have been few studies on the behaviour problems of preterm-born infants during infancy and at preschool age. Fourteen cohort studies published in PubMed and PsycINFO between 2000 and 2012 were reviewed with a focus on the type, occurrence, comorbidity, stability, prediction, perinatal, social, and relational risk factors for behaviour problems of preterm-born children in infancy (0-2y) and at preschool age (3-5y). The relational risk factor was considered in an additional four papers. Very-preterm, very-low-birthweight, and moderately-preterm children, in both age groups, show more behaviour problems than term-born comparison children even after perinatal and social risk factors and cognitive performance have been controlled for. Poor social/interactive skills, poor behavioural and emotional self-regulation, emotional difficulties, and reduced attention are the most common behaviour problems. Behaviour problems in infancy are predictive of later behaviour problems and they should be included in follow-up programmes.The survival of preterm infants has steadily increased over the last few decades thanks to continued progress in perinatal care. It was previously feared that this higher rate of survival among the preterm population came at the expense of an increase in severe impairments, but rates of cerebral palsy and sensory deficiencies have, in fact, decreased.1 Conversely, the rates of subnormal cognitive function in infancy have remained unchanged during the last decades 2 and preterm infants remain at higher risk of later developmental abnormalities in childhood.3 In particular, 'high-prevalence and low-severity' disabilities such as learning disorders and behaviour problems are still common conditions in preterm-born children at school age.3-5 The term 'behaviour problems' is currently used for a wide spectrum of difficulties in behavioural self-regulation, including hyperactive/aggressive behaviour; interactive, attention, sleep, eating, and sensory sensitivity problems; as well as anxiety, depression, and somatic symptoms.At school age, studies performed with screening questionnaires provide evidence of behaviour problems characterized by inattention/hyperactivity and social and emotional difficulties.3,5 These findings are confirmed by studies based on psychiatric evaluations that yield diagnoses of psychiatric disorders. The most prevalent disorder is the inattentive subtype of attention-deficit-hyperactivity disorder, with an estimated prevalence of 7 to 23%, followed by emotional disorders such as anxiety (9%), and autism spectrum disorders (3.6-8%). 4,5 As far as infancy is concerned, the behaviour problems of preterm infants were first mentioned in 1939, long before the intensive care era, when Shirley, 6 described a behavioural syndrome that was primarily characterized by motor and speech difficulties, hyperactivity, irascibility, susceptibility to distraction, shyness, and overdependence on the mother. Three de...