Background: Asthma is one of the most common chronic respiratory conditions affecting young children. It is estimated that asthma affects 20% of schoolchildren in South Africa. The school setting represents “home” for most children, and teachers are recognised as in loco parentis. Therefore, it is imperative that primary school teachers have sufficient knowledge of asthma and its management, in order to be able to make rational and safe decisions about the children in their care. This study was undertaken to assess the levels of asthma knowledge and its  management among primary school teachers.Method: Data were collected from 226 consenting schoolteachers in 19 randomly selected primary schools in the Umdoni sub-district of KwaZulu-Natal, using a cellular telephone Mobile Researcher® application. A total of 55 questions relating to knowledge of asthma were posed, together with questions about motivation for, and confidence in managing, an asthmaemergency.Results: Overall, 38.5% of teachers were able to answer < 50% of the knowledge questions correctly. Teachers’ level of asthma knowledge was not significantly associated with age, gender, years of teaching experience, educational qualification, or contact with an asthmatic individual (p-value = 0.153, p-value = 0.870, p-value = 0.070, p-value = 0.082 and p-value =0.176, respectively). Areas of particular concern included knowledge  regarding the signs and symptoms of a severe acute asthma attack, asthma medication and management, and asthma and sports.Conclusion: This study demonstrates deficiencies in teachers’ knowledge of asthma, which will need to be addressed if they are to safely discharge their duty of care. Teachers are supportive of in-service training in asthma management