Background: Depression is a common mental disorder in adults, and the World Health Organization (WHO) has ranked it as the fourth leading cause of disability worldwide. Doctors are not immune to the disorder; in fact, they have a higher risk than the general population, which affects the physician’s life and compromises the quality of the health services. In Saudi Arabia, resident doctors’ mental health is under-recognized, and more studies need to be conducted to fill this gap. Objectives: This study is aimed at determining the prevalence of depression among resident doctors working at a tertiary care hospital in Riyadh, and analyzing the associated factors. Methodology: The study utilized a cross-sectional design. The resident doctors in KFMC hospital in Riyadh participated in this study by filling questionnaires, including a depression-screening instrument (CES-D), a sociodemographic datasheet, and questions about other associated factors. Results: One hundred and nineteen residents responded with an overall response rate of 70%. Based on categorical levels of the CES-D, 41% (49) did not have depression, 20% (24) had mild to moderate depression, and 39% (46) had probable major depression. There were significant differences in depression by gender with higher rates among women (55.1%) than men (27.1%). Further, participants with a history of depression were more likely to have depression (62%).