Background: Emergency medical services employees, the first people providing pre-hospital services for critically ill or injured patients, are constantly exposed to many stressful factors that can lead to job burnout in the long run. The level of job burnout varies according to employees' personality traits. Objectives: The present study aimed to investigate job stress and job burnout based on the personality traits of emergency medical service technicians of the Tehran Disaster and Emergency Medical Management Center. Methods: This cross-sectional, descriptive study was conducted in 2018 on all operational staff of the Tehran Disaster and Emergency Medical Management Center (N = 1551). A sample of 308 personnel was selected using the stratified random sampling method proportional to size and simple random sampling method. The required data was collected using a four-part questionnaire which measured demographic characteristics and included the Health and Safety Executive Job Stress Questionnaire, the Maslach Burnout Questionnaire, and the revised Costa and McCrae NEO Five-Factor Inventory (NEO-FFI). The collected data was analyzed using SPSS 22.0. Results: Reducing exhaustion, job stress, and neuroticism and strengthening conscientiousness and agreeableness among emergency medical services employees are very important issues. Reducing working hours, examining factors of dissatisfaction and stressors in the workplace, and improving welfare facilities can decrease job burnout among employees. Moreover, the heads and managers of pre-hospital emergency services should plan to provide continuous training in stress management skills at emergency bases in order to reduce job stress among employees.