Background: Bullying is an ever-present problem occurring within preparatory schools across the world. Bullying creates personal, social, and emotional, as well as academic problems for the victim. Therefore, this study was aiming to assess bullying behaviors and its effect on preparatory school students. This study was conducted on 400 students in preparatory school students in Ashman city of Mounofyia government. Data were collected using: 1) Interviewing questionnaire including the following parts: A) Socio-demographic sheet. B) bullying behavior scale. C) victim scale and D) effects of bullying behavior on preparatory school students. The result of this study showed that more than half of students under study (56.75 %) sometimes perform social bullying behaviors, nearly half of them (44.75%) perform verbal bullying behaviors and less than half of students under study (41.75%) sometimes perform physical bullying. Also, about two fifth of students under study (39,75%) sometimes exposed to physical bullying behaviors and more than two fifth of them (45%) exposed to verbal bullying behaviors and 69% of them have moderate physical effect, also 59.25% of them were had moderate psychological effect and42.5 of them were had moderate social effect and moderate impact on academic achievement. Study concluded that preparatory school students sometimes perform (physical, verbal, and social) bullying behavior and male students were involved in bullying behavior more than female. More than two fifth of victimization exposed to verbal and social bullying. In addition, there was a highly statistically Significant relation between type of bullying and effects of bullying behavior. The study recommended designing and implementing a counseling program geared towards preparatory school students to guide them on how to avoid and/or deal with bullying behavior to prevent psychosocial problems and improve academic achievements.