Background: Medical students and practicing physicians, in comparison with the general population and that of other professions, are exposed to academic and professional stress and therefore are vulnerable to psychosocial health problems and certain specific dysfunctions that may compromise their physical, mental, and social health. Objectives: To determine the prevalence of depression, anxiety and stress among the undergraduate medical students. Methods: A cross-sectional questionnaire based study was conducted among undergraduate second and final year part I medical students from Rangaraya Medical College, Kakinada, Andhra Pradesh, India using Depression Anxiety and Stress Scale (DASS) 21 in August 2012. Results: Data analysis was done on Statistical Package for the Social Sciences SPSS version 16. A total of 330 students participated in the study. Our study found that the overall prevalence of depression was 45.4%, anxiety was 64.9% and stress was 40.0% among all participated medical students. Conclusion: The higher level of psychiatric morbidity depression, anxiety and stress among undergraduate medical students warrants needs for strategic plans to alleviate depression, anxiety and the stressors right from the time they join medical school and has to be continued till they finish the course.