[en] Heavy metals are the most widespread and harmful contaminants of environment. Cadmium and lead compounds have a particularly high genotoxic action. In addition, long-term, low-dose chronic irradiation occurs most frequently in nature. Thus, the goal of the present work was to study the effect of salts of heavy metals, lead and cadmium, on the cytogenetic damage in bone marrow cells of rats exposed to chronic and acute gamma irradiation, as well as on the magnitude of the adaptive response induced by chronic irradiation. Adult male rats were exposed to chronic gamma irradiation at low dose rate from ¹³⁷Cs in a gamma-chamber (dose rate of 0.0013 Gy/h). Cumulative doses of chronic irradiation were 3, 9, 21 and 40 cGy at 1, 3, 7 and 14 days of exposition, respectively. Solutions of heavy metals Pb(CH₃COO)₂ . 3H₂O and CdCl₂ . 2.5H₂O (50 mg/l) were given per os throughout the period of chronic irradiation. Rats subjected to chronic irradiation with an appropriate dose were immediately subjected to single acute dose 4 or 6 Gy (dose rate 47 cGy/min). Chromosome preparations of bone marrow cells were carried out by standard procedures. Percent of cells with aberrations and all types of chromosome aberrations were recorded. Five animals were used in each experiment. From each animal 100-200 cells were scored. The results of this study indicate that the administration of heavy metal salts to the diet of rats 1) enhances the cytogenetic damage in unirradiated animals; 2) increases the genotoxic effect of chronic and acute irradiation; 3) slightly decreases the value of the adaptive response induced by chronic irradiation. (author)