Аннотация:The cytogenetic effects of two chemical agents, hydroxylamine used for the destruction of bacterial cells and thimerosal added to many immunobiological preparations as preservative, were studied in vivo by their action on the marrow cells of C57BL/6J mice. The preparations under study, when injected intraperitoneally in a wide range of doses, including subtoxic ones, induced no chromosomal aberrations. At the same time cyclophosphamide, an antitumor cytostatic agent used for positive control, produced a pronounced damaging effect on chromosomes.