The aim of this study was to investigate radioprotective properties of Echinacea purpurea tablets in vivo. We analysed lymphocyte chromosome aberrations (CA), micronuclei (MN), apoptosis of leukocytes and haematological parameters in a group of radiation workers who were identified as carrying dicentric chromosomes in their lymphocytes. All radiation workers were taking two 275 mg Echinacea tablets b.i.d., according to a pharmacist's recommendation. All parameters were analysed before and after the two-week treatment. At the end of the treatment lymphocyte CA frequency dropped significantly, and the number of apoptotic cells increased. The inverse lymphocyte-to-granulocyte ratio at the beginning of the study changed to normal at its end. In conclusion, biological effects observed after administration of Echinacea purpurea preparation suggest that it may be beneficial for the prevention of adverse health effects in workers exposed to ionising radiation.