Ionizing radiation affects the expression of adhesive and co-stimulatory molecules in lymphocytes. The physiological function of cellular isoform of prion protein (PrP(c)) is little known. Evidences indicate a link between lymphocytes activation and PrP(c) expression on their surface; however, no direct effect of radiation on PrP(c) level in these cells was investigated. The objective of this study was to determinate the effect of low doses of ionizing radiation on the expression of PrP(c) on the surface peripheral blood lymphocytes in the women operating X-ray equipment. In 36 female workers and 30 persons of the control group the PrP(c) expression on CD3 (T lymphocytes), CD4 (T helper), CD8 (T cytotoxic) and CD19 (B lymphocytes), as well as the percentage of lymphocytes with PrP(c) on their surface, were tested. Subgroups with respect to age and length of employment were selected. A significant increase was observed in PrP(c) expression on CD3 and CD4 with lowered PrP(c) level on CD8 and percentage of CD8 cells with PrP(c) in workers compared to control. The PrP(c) level did not show significant changes in subgroups in relation to age (below and over 40 years old) both in the investigated and control groups, whereas a lower percentage of PrP(c) expressing CD19 cells showed in employed women below 40 years of age. A significant decrease was found in PrP(c) expression on the surface of CD3, CD4 and CD8 cells in the subgroup employed for over 10 years than in the subgroup with less than 10 years of employment.