Background: Mothers of ADHD children often display high levels of distress. Understanding the origin of such distress in a view to reducing it is an essential part of the clinical management of ADHD children. Studies have shown that children’s symptoms are linked to mothers’ stigma and that such stigma can cause mothers’ distress. However, no study has explored the links between symptoms, stigma and distress. Aim: We tested (1) whether children’s symptoms are sources of affiliate stigma, which in turn contributes to generating mothers’ distress and (2) whether such relationship is stronger in mothers of male ADHD children. Method: 159 French mothers of an ADHD child were recruited. Four indices were used to assess mothers’ distress: anxiety, depression, self-esteem and life satisfaction. Children’s ADHD symptoms and mothers’ affiliate stigma were also measured and contrasted with distress. Results: Mothers’ distress was positively related with both affiliate stigma and children’s ADHD symptoms, but this was only true in mothers of male ADHD children. The relationship between children’s symptoms and mothers’ distress was mediated by affiliate stigma. Conclusions: Psychosocial interventions in mothers of ADHD children must integrate affiliate stigma and should be adjusted according to child’s gender.