Background: Attention deficit hyperactivity disorder (ADHD) is the most common neurobehavioral disorder in children and adolescents. It is characterized by inattention and hyperactivity-impulsivity that often results in behavioral and academic difficulties. It affects about 3 - 12% of children with a male to female ratio varying from 3:1 to 9:1.Objectives: To estimate the prevalence and identifying possible risk factors of attention deficit hyperactivity disorder among preschool children (3-6 years), at Menoufia governorate. Methods:  A cross-sectional comparative study was carried out in Menoufia governorate during the period from 15^th March 2016 to 1^st April 2018. The study included 572 preschool children (308) male and (264) female. They had been chosen from the preschool classes (KG1and KG2) in the randomly selected schools. Written consents were taken from children caregivers to participate in the study. Parents and teachers were the respondent to the Arabic version of Conner's questionnaire. Suspected cases were confirmed and categorized by DSM-V criteria. Affected children and control group were subjected to medical and psychological assessment, IQ estimation and laboratory investigations. Results: Prevalence of attention deficit hyperactivity disorder among preschool children was 9.30%. It was higher in males (69.8%) with a male to female ratio about 2:1. Main risk factors were low socioeconomic level, large family size, living with a single parent and positive consanguinity. Conclusion: ADHD presents a troublesome problem among preschool children at Menoufia governorate. Collaborative efforts are required for early detection and management.