This study aimed to find the association between job satisfaction and radiation protection knowledge, attitude and practice of medical radiation workers occupationally exposed to ionizing radiation. In this cross-sectional study, 530 radiation workers affiliated to Tehran University of Medical Sciences completed a knowledge, attitude and practice questionnaire on protecting themselves against radiation and Job Descriptive Index as a job satisfaction measure during May to November 2014. Opportunities for promotion (84.2%) and payment (91.5%) were the most important factors for dissatisfaction. Radiation workers who were married, had more positive attitudes toward protecting themselves against radiation, and had higher level of education accounted for 15.8% of the total variance in predicting job satisfaction. In conclusion, medical radiation workers with a more positive attitude toward self-protection against radiation were more satisfied with their jobs. In radiation environments, improving staff attitudes toward their safety may be considered as a key strategy to increase job satisfaction.