['To determine whether children with asthma and on inhaled corticosteroids have more behavioural problems, such as aggressiveness and hyperactivity, as compared with healthy controls and with children under medical care because of other disorders.', 'Questionnaires were given to three groups of children: a group of asthmatic children with inhaled corticosteroids (ICS), a group of children attending the ear, nose and throat (ENT) outpatient clinic and the healthy controls. Included were questions about health, medication use, demographical data and about behaviour, including the child behaviour check list (CBCL) and questions about attention deficit hyperactivity disorder (ADHD).', 'Forty asthmatic children on ICS, 50 children visiting the ENT outpatient clinic and 183 healthy controls were studied. The total CBCL and mean ADHD scores of the children on ICS were 28.1 and 9.1, which were both significantly higher than the scores of the healthy controls (20.4 and 7.1), but not when compared with the ENT outpatient group (26.2 and 8.6). Further analysis revealed statistically significant differences between the ICS group and healthy controls in CBCL-axes. There were, however, no differences between the ENT group and the ICS on one side and the healthy controls on the other.'] Do inhaled corticosteroids affect behaviour?