Introduction: Nowadays, emotional reactions such as stress, anxiety and depression are known as inseparable component of modern nursing, which cause problems for nurses and patients. Objective: This study aims to determine the level of depression, anxiety and stress in nurses in selected educational hospitals affiliated to a chosen university in Tehran city. Methods: In this cross-sectional study, 413 employed nurses in educational hospitals affiliated to a selected university were chosen and a two part questionnaire was used which included demographic characteristics and Depression, Anxiety and Stress Scale questionnaire. Results: Study findings showed that 25.8% of nurses suffered depression, 21.6% had anxiety and47.6% had stress. Results showed significant relationship between depression, anxiety and nurses marital status (P