Headache is a potentially disabling condition involving enduring pain that negatively influences the quality of family life. Behavioural problems are more common in children with headache and are potentially associated with higher levels of parental stress. The aim of this study was to evaluate the extent to which children's behavioural problems were associated with maternal stress and how the child's perception of security in the maternal attachment relationship moderates this association. Seventy‐one school‐aged children with headache (headache group (HG), age M = 9.8 years old, SD = 1.3) and 71 children from a low‐risk normative population (control group (CG), age M = 9.2 years old, SD = 1) and their mothers were involved in the study. Mothers' reports of children's behavioural problems were associated with higher maternal stress in the caring task both in the HG and in the CG. Results also showed that the HG was more at risk for behavioural problems, whereas no difference between groups was detected for parenting stress and for attachment insecurity. In children with headache, perception of attachment security decreased the strength of the association between maternal stress and externalizing behavioural problems. Secure attachment may provide children with headache and their parents with support in managing the negative emotions that arise in the context of significant health issues. Implications for practice are discussed. Copyright © 2015 John Wiley & Sons, Ltd.