Personality disorders (PDs) represent a common and serious public health problem. The aim of the present work was to determine the prevalence of different PDs among first grade students of Alexandria University and to investigate some ecological factors of the problem. A cross-sectional study was carried out and included 1086 students. The Arabic Version of Personality Diagnostic Questionnaire-4+(PDQ-4+) was applied. Results revealed that more than one quarter of the studied sample had at least one PD (26.1%). Cluster C was the most frequently occurring (24.9%). The commonest subtypes recorded were avoidant PD (20.4%) and obsessive-compulsive PD (20.2%) followed by paranoid PD (15.0%). Significant predictors of PD delineated on the logistic regression analysis were mainly psychosocial factors including parental inconsistent discipline, intrafamilial conflicts, parental rejection and control, decreased familial and friends' social support, and sexual abuse. A positive history of conduct disorder, chronic medical illness or psychiatric problem also significantly predicted the occurrence of PD. Lack of freedom in college selection and smoking emerged as recent events that predicted the PD status of students