The hospital industry is one of the industries with a number of different occupational hazards. This is why individuals in the industry have good compensation and adequate protection. On top of the list for high level of protection is the field of medical radiation. Various institutions in the field follow certain guidelines to promote safety. Health care workers expect labor unions to cooperate with hospital managements for the promotion of their safety in the work place. This study aims to determine the relationship of labor unions in the promotion of radiation safety in hospitals, and to pinpoint the aspects for improvement. A survey was conducted to the employees in unionized and non-unionized hospitals using questionnaires with principles based from the International Atomic Energy Agency (IAEA) and the Magna Carta of Public Health Care Workers. Four unionized and three non-unionized private tertiary hospitals in Metro Manila having a bed capacity of 150 and more were featured in the study. The t-test was used in measuring the statistical significance of the differences of the responses between the unionized and non-unionized employees with regards to their institutions’ compliance to radiation safety. The analyses of data showed that the existence of labor unions in a medical establishment does not have a significant influence in its effective compliance with the radiation safety principles.