Background: Burnout during stressful dental residency courses can adversely affect the personal abilities and competencies of residents. This study aimed to investigate burnout and its relationship with spiritual intelligence in Mashhad Dental School residents in 2019-2018. Methods: In this cross-sectional descriptive-analytical study, approximately all the dental residents of Mashhad Dental School participated in the survey. Demographic information questionnaire, Maslach burnout questionnaire, and David B. King’, s (2008) Spiritual Intelligence Scale were used to collect data. Finally, SPSS software (version 20) was employed for data analysis. Results: Overall, 53 women (52%) and 49 men (48%) with a mean age of 27. 83 years participated in this study (a response rate of 97%). The mean score of burnout was 58. 75. Residents also had a low reduced personal accomplishment, moderate emotional fatigue, and moderate depersonalization. The mean scores of spiritual intelligence and its sub-scales, including critical existential thinking, production of personal meaning, awareness transcendence, and consciousness expansion were 51. 91, 15. 66, 13. 19, and 14. 67, respectively. Personal accomplishment was significantly correlated with overall spiritual intelligence (P < 0. 001, r = 0. 404) and its sub-scales, including producing personal meaning (P = 0. 009, r = 0. 26), transcendental awareness (P < 0. 001, r = 0. 382) critical thinking (P = 0. 04, r = 0. 2), and conscious state expansion (P < 0. 001, r = 0. 356). Eventually, there was no significant difference between burnout and spiritual intelligence and their sub-scales regarding gender, marital status, and school year (P < 0. 05). Conclusions: Mashhad Dental residents showed moderate levels of emotional fatigue and spiritual intelligence. Accordingly, there is a need for planning strategies to reduce burnout.