Medical plants and their various extracts have been occasionally used in the treatment of many diseases. Astragalus is one of those medical plants and it has several biological activities. In the present study, the hexane extracts of six Astragalus species, which are grown in the eastern Anatolia region of Turkey, were isolated, and their mutagenic and antimutagenic properties were investigated by using Salmonella typhimurium TA1535, TA1537 and Escherichia coli WP2uvrA tester strains at 0.05, 0.5 and 5 microg/plate concentrations. Known mutagens sodium azide (NaN(3)), 9-Aminoacridine (9-AA) and N-Methyl-N'-nitro-N-nitrosoguanidine (MNNG) were used to determine antimutagenic properties of hexane extracts. The results showed that all hexane extracts, investigated in the present study, can be considered genotoxically safe because they do not have mutagenic activity at the tested concentrations. But, a great many of them have antimutagenic activity against 9-Aminoacridine known as a model intercalator agent. The inhibition rates obtained from the antimutagenicity assays ranged from 27.51% (A. macrocephalus--0.05 microg/plate) to 54.39% (A. galegiformis--5 microg/plate). These activities are valuable toward an extension of the employ of these drugs as new phytotherapeutic or preservative ingredients.