It is generally accepted that Attention-Deficit/Hyperactivity Disorder (ADHD) results from a dysfunction of the central nervous system, which has led to a commonly held belief that environmental factors play little role in the behavioural problems of children identified as having ADHD. Therefore, the two studies reported in this article investigated the relationship between parental divorce and the psychological well-being of children with ADHD. Subjects, aged 6 to 18 years, were diagnosed with either the inattentive or combined subtype of the disorder. Firstly, differences in children's behaviour between divorced and non-divorced families were examined, and subtype, age, and gender differences were evaluated in terms of symptom severity and comorbid conditions. Secondly, parents' perceptions of the impact of their children's behaviour on marital status and family/parental functioning were examined. Parental divorce was associated with greater symptom severity, more externalizing/internalizing behaviours, and poorer social functioning, but less with academic underachievement. Further, parental divorce was related to adjustment differences in ADHD subtypes, age, and gender. However, the correlation between behaviour problems of children with ADHD and marital/family dysfunction was weak. It may be concluded that parental divorce was associated with the psychological well-being in children with ADHD, and there is some suggestion that ADHD should be viewed as a bio-psychosocial disorder.