Among 1648 asthmatic patients, 17 families (1%) were identified as having Munchausen syndrome by proxy. Ten families did not treat their children's, attacks or refused medical care, and seven exaggerated the severity of symptoms to obtain invasive investigations and treatment. All the families had disturbed psychosocial backgrounds. The abuse consisted mainly of neglect, in that necessary treatment was not given. In some cases a more direct form of abuse was observed, when useless and sometimes harmful investigations and treatment were given. We conclude that medical control of the compliance of both parents and children is necessary in the management of childhood asthma.