In the present study we analyzed and followed up on the cytogenetic effects of low levels of ionizing X-radiation on hospital workers at 72 h cultures. Samples of peripheral blood were collected from 10 hospital workers exposed to 1.84 mSv/year, and from 10 non exposed individuals, who were screened simultaneously and used as controls. The chromosomes were prepared using standard techniques. After 12 months, we undertook a second evaluation, this time with exposure to the same workers of 1.67 mSv/year. We observed 100 metaphases per subject, and there was a high percentage of altered metaphases (29.2% in the first sample and 26% in the second samples) The chromosome analysis in the second mitotic division, show aberrations such as gaps, breaks and acentric fragments, as well as other alterations such as dicentrics and rings, as well as chromosome variants (double minutes) in the exposed workers vs. the controls, and the difference was statistically highly significant (p < 0.001). There is no statistically significant difference between the first sample of exposed workers with the second one (p > 0.05). The findings in this study are interesting, because the workers were exposed to doses well below the accepted standards for exposure to radiations. Because of these unusual findings, our results could have potentially major consequences on our views on standards of exposure to radiation.