WHAT'S KNOWN ON THIS SUBJECT: Several studies have shown that behavioral problems can be associated with defecation and voiding disorders, although few studies have looked directly at a link between a diagnosis of attention-deficit/hyperactivity disorder (ADHD) and constipation or fecal incontinence. WHAT THIS STUDY ADDS:We identified an increased risk for both constipation and fecal incontinence in children with ADHD. In patients with concomitant ADHD and defecation disorders, more aggressive medical and behavioral treatment of the constipation or fecal incontinence may be warranted. abstract OBJECTIVE: Functional constipation and fecal incontinence are common childhood gastrointestinal conditions. Both conditions may be associated with behavioral problems. Attention-deficit/hyperactivity disorder (ADHD) is the most common behavioral disorder of childhood, characterized by shortened attention span and hyperactivity. We hypothesize that a diagnosis of ADHD increases the risk for functional constipation and fecal incontinence. METHODS:A retrospective cohort study of children was performed by using the military health system database. Children of active-duty military personnel, aged 4 to 12 years, from October 2005 to September 2007, were included. ADHD, constipation, and fecal incontinence were identified by International Classification of Diseases, Ninth Revision, Clinical Modification diagnostic codes. Relative risks and adjusted incidence rate ratios (IRRs) were calculated. A subgroup analysis of subjects receiving medical therapy was performed.RESULTS: There were 742 939 children identified in the study, 32 773 (4.4%) of whom had ADHD. Children with ADHD had an increased prevalence of constipation (4.1% of children with ADHD vs 1.5% children without ADHD; P , .001) and fecal incontinence (0.9% of children with ADHD vs 0.15% of children without ADHD; P , .0001). Children with ADHD had more visits than those without ADHD for both constipation (IRR 3.39; 95% confidence interval 2.59-4.43) and fecal incontinence (IRR 7.74; 95% confidence interval 5.01-11.98). Children with ADHD receiving medicinal therapy did not differ significantly from children with ADHD not receiving medicinal therapy on rates of constipation visits (P = .57) or fecal incontinence visits (P = .32). CONCLUSIONS:Children with ADHD are significantly more likely to have constipation and fecal incontinence. Medical therapy for ADHD does not impact visit rates for defecation disorders.