BackgroundAsthma is the most prevalent respiratory disease caused by chronic airway inflammation. Attention Deficit Hyperactivity Disorder (ADHD) is children's most common psychological and neurodevelopmental disorder. Increased risk for ADHD in patients with inflammatory and autoimmune diseases supports the role of inflammatory mechanisms in the occurrence of ADHD. However, the association between asthma and ADHD remains unclear.ObjectiveThis study was designed to evaluate the prevalence of ADHD in patients with asthma who were referred to the clinic of allergy and clinical immunology.MethodsThis cross-sectional study was conducted on children aged 6 to 18 with asthma at Imam Ali hospital, Karaj, Iran. The patient's demographic data, history of childbirth delivery type, premature birth, hospital admission, family income, birth rate, and family history information related to the patient's asthma and medicines were recorded. ADHD diagnosis was made using the Persian version of Conners Parent Behavioral Problems Rating Scale (CPRS-26).ResultsIn this study, 677 asthmatic patients were enrolled; 46 patients (6.8%) had ADHD. The probability of ADHD in asthmatic patients inhabited in a rural area, males, and patients with a history of food allergy, allergic rhinitis, urticaria, and eczema was significantly higher (p < 0.05). In addition, our result demonstrated that the likelihood of ADHD in patients with asthma and a history of PICU admission was significantly higher (p < 0.05).ConclusionsThe present study showed that severe asthma, was the risk factor for ADHD in patients with asthma. Physicians should be aware of this co-morbidity to refer asthmatic patients who have the symptoms of ADHD to a psychologist.