Background Occupational, environmental, or experimental exposure of people, animals, and cell cultures to radon has been the subject of numerous studies. The present study comprised 120 miners, occupationally exposed to radon and heavy metals in a Pb‐Zn mine; 57 female subjects environmentally exposed (control group 1); and 100 subjects from the urban population (control group 2). Methods Radon measurements were performed, and the effective equivalent radiation doses over a 2‐year period were calculated. The following end points were studied: conventional analysis of structural chromosomal aberrations, micronuclei, and sister chromatid exchanges (SCE). Results The mean values of the percentage of structural chromosomal aberration frequency were 4.09% in miners, 1.43% in control group 1, and 1.88% in control group 2. The difference in frequencies was statistically significant (AV/FP 0.000). The frequency of micronuclei was 13.00 ± 3.54 per 500 CB cells in miners and 6.4 ± 2.11 per 500 CB cells in control subjects (AV/FP 0.000). The frequency of SCE was 7.97 per cell in miners (range 6.2–13.1) and 6.17 and 6.63 for the two control groups, respectively (AV/FP 0.000). Conclusions Comparative analysis of the cytogenetic results for all three groups showed significant differences between the miners and the two control groups. The findings of this study need to be interpreted with regard to simultaneous exposure to radon and metals, i.e., lead, cadmium, and zinc. Am. J. Ind. Med. 34:455–463, 1998. © 1998 Wiley‐Liss, Inc.