Background: Medical study often carries a great load on the medical students that may result in different affections on their life. Objectives: To assess the prevalence of stress and burnout and the influencing factors that may contribute to them among the Egyptian medical undergraduate students and to determine the most influencing stressors in the pre-clinical and clinical stages of education. Method: A cross-sectional study was conducted on 320 undergraduate Egyptian medical students in the Zagazig and Menoufia faculties of medicine. The participants were interviewed through a questionnaire of four parts. The first part was about their sociodemographic characteristics, the second part was to assess their perceived level of stress by the 12-item General Questionnaire (GHQ-12), The level of burnout was assessed through the Maslach Burnout Inventory (MBI) in the third part, and stress and burnout influencing factors were assessed through a predesigned questionnaire in the fourth part. Results: This study showed a worrisome prevalence of stress (84.7%) and burnout (45.6%) among undergraduate medical students. On studying stress, the students in the clinical stage of education were exposed more to stress and burnout (P-value 0.007, <0.001). The most stressing factors were being in clinical education, having a personal illness or disability that may affect their academic performances, and worry about the future career. Conclusion: High prevalence of stress and burnout is disconcerting. There were many triggering factors found that should be reconsidered.