Adherence to inhaled steroids is suboptimal in many children with asthma and can lead to poor disease control. Many previous studies in paediatric populations have used subjective and inaccurate adherence measurements, reducing their validity. Adherence studies now often use objective electronic monitoring, which can give us an accurate indication of the extent of non-adherence in children with asthma. A review of the studies using electronic adherence monitoring shows that half of them report mean adherence rates of 50% or below, and the majority report rates below 75%. Reasons for non-adherence are both intentional and non-intentional, incorporating illness perceptions, medication beliefs and practical adherence barriers. Interventions to improve adherence in the paediatric population have had limited success, with the most effective containing both educational and behavioural aspects.