Cytogenetic analysis of blood lymphocytes can be used as a biomarker of absorbed radiation dose. The frequency of chromosomal aberrations (CA) correlates with subsequent cancer incidence. Healthy medical employees in Hungary - 301 working in an ionizing radiation work area and 732 controls - were studied from 1997 to 2022. Frequencies of chromatid- and chromosome-type aberrations in peripheral blood lymphocytes were significantly higher in the ionizing radiation group. Smoking also affected the frequency of aberrations, which was highest among smokers in the radiation group. Staff working with ionizing radiation were divided into four groups: CT, radiation therapy, diagnostic X-ray, and nuclear medicine. Total aberrations and aberrant cells were significantly higher in the nuclear medicine group than in the CT group. Tumor cases were not more frequent among the ionizing radiation group than among the control group.