Objectives: The aim of the study was to determine the prevalence of attention deficit hyperactivity Disorder (ADHD) and associated risk factors among children were attended the general pediatric outpatient clinic of Menoufia University Hospital. Background: Attention deficit hyperactivity disorder is the most commonly seen developmental disorders, with significant impacts on the child's social, psychological, and scholastic functioning. Methods: The study was conducted on 600 children (5-12 years) were attended the general pediatric outpatient clinic of Menoufia University Hospital. All studied patients were subjected to adequate history taking, full clinical examination, a questionnaire regarding socioeconomic, family and maternal variables and a parent-completed, ADHD Rating Scale of attention deficit hyperactivity symptoms was used. Results: The study revealed that the prevalence of probable ADHD in our study was 19.7%. and was higher in males than in females with a ratio 2.7:1. The most common type of probable ADHD was the combined type and the least frequent type was the inattentive type. There were many factors that were sought to be associated with increase possibility of developing ADHD. Conclusion: The present study shows a high prevalence of probable ADHD in children. our study also revealed that probable ADHD was associated with many risk factors, prevalence was high in the male sex, living in urban areas, low socioeconomic families, large family size, living with a single parent, family history of ADHD, preterm children, low birth weight and bottle fed children.