Acne vulgaris is the most common skin condition affecting adolescents across the globe. It is a chronic inflammatory disease of pilosebaceous follicles, characterized by the presence of comedones, papules, pustules, nodules, cysts and scars. Development of acne has been associated with many factors as genetic component, emotional stress, diet and hormonal activity such as menstrual cycles and puberty. Objectives: To estimate the prevalence of acne in adolescents at preparatory and secondary school students in Belbeis city and to identify the risk factors that may have an impact on acne. Methods: A cross sectional study was conducted on 370 adolescents aged 10-19 years in Belbeis city. A sociodemographic and risk factors questionnaires of acne was applied on students of two preparatory schools and one secondary school. Results: Among the study subjects; 21.6% reported having acne. Acne is more significant in females than males and in students in preparatory schools than students in secondary schools with P-value = 0.04 and 0.01 respectively. There is high significant difference between female students who have acne and female students who do not have acne regarding occurrence of menarche and increasing acne few days before menses, there is weak significant difference regarding consuming large amounts of high fat milk products in diet. The occurrence of acne is one and half time higher in students with positive history of acne in their families. Conclusion: Twenty percent of adolescence students had acne, with girls affected at higher rates than boys.