Background: Parenting is one of life's most difficult role which influences children behavior. Through effective discipline children learn self- discipline and exhibit lower levels of children's aggressive behavior .Aim of the study was to explore the role of parenting styles in aggressive behavior among preschoolers children. Subjects & Methods: Research design: A cross - sectional descriptive design was used to achieve the aim of the current study. Setting: The study was conducted at two nursery schools from each educational zone available at Zagazig City Subjects: A purposive sample of 661 parents and their preschoolers' children who fulfilled the study inclusion criteria. Tools of data collection: One tool was used in the present study which composed of three parts, the first was a socio-demographic questionnaire, the second was The Parenting Practices Questionnaire (PPQ) and the third was Aggressive Behavior Scale. Results: revealed that the most commonly used parenting style in the studied sample was authoritative parenting style presented (90.91%) among mothers and (87.62%) among fathers. Preschooler children exhibited moderate aggressive behavior (45.08%) which appeared to increase in children whose parents were authoritarian or permissive and decrease in children whose parents were authoritative. Conclusion: Authoritarian and permissive parenting styles were positive predictors for aggressive behavior of preschooler children. Recommendations: Health education programs especially for young age parents about appropriate parenting styles and educate them about how to manage aggressive behavior of their children