Self-management of asthma allows patients to fine tune treatment and is preferable to recurrent consultations. Peak flow measurement is commonly used as an objective measure of change in airway function associated with deteriorating asthma. Self-management plans offer information about levels of change in peak flow which require patients to respond by treatment changes or by seeking medical help. Self-management of asthma in adults appears more effective when accompanied by education and guidance about when and how to make such changes. Peak flow in children is less reliable and it's role in self-management is therefore unclear. The aim of this study was to compare peak flow plus symptom based management with symptom-based management alone in school children with asthma. A randomised, controlled trial was performed. One hundred and seventeen children were recruited via General Practitioners and hospital clinics and each studied for approximately 16 weeks. After a 4 week run up period, ninety children were randomised to receive either peak flow and symptom based management or symptom based management alone. All children performed twice daily spirometry at home, unsupervised and completed a symptom diary every morning. They were visited at approximately 4 weekly intervals. At each visit quality of life and use of health services were recorded. There were no differences in mean daily symptom score, lung function, quality of life score or use of health services between the groups over time. During acute episodes children responded to changes in symptoms, irrespective of the randomisation group, so that peak flow did not contribute to self-management decisions. In conclusion, knowledge of peak flow did not add significantly to the management of asthma in these children, even during acute exacerbations.