OBJECTIVE The study aims to assess the change of peripheral blood cell numbers following protracted low-dose radiation exposure among medical radiation workers. METHODS A cohort of 375 Chinese medical workers were followed for 5 years (2015-19) and recorded the changes in blood cells and cumulative doses. T-test, least significant difference-T test, variance analysis and correlation analysis were utilized in this study. RESULTS Compared with the control group, the white blood cells, hemoglobin counts and the ratio of eosinophils in the study group showed a downward trend. The differences in blood cells between groups were mainly found in the number of red blood cells. In a short cumulative time, such as 1 or 3 years, a correlation between the cumulative dose and the quantity of blood cells was detected, but not at 5 years. CONCLUSIONS There is no significant difference in the blood cell counts between different types of work, and the long-term cumulative dose has not been statistically correlated with the number of blood cells. So that the number of peripheral blood cells can no longer be used as a good indicator of radiation damage.