The present study focuses on the clastogenic effect of ginger rhizome. Crude aqueous extracts of ginger were garaged at doses of 0.5, 1, 2, 5, 10 g/kg body weight and ginger oil (0.625, 1.250 and 2.50 ml/kg body weight) was administered by intraperitoneal injection to male mice. Chromosome damage was studied in a preparation made from bone marrow cells following colchicine injection to all farce and examination of the cells after pretreatment in hypotonic solution, fixation, air drying and staining in Giemsa solution. Attention is drawn to the weakness of the clastogenic activity expressed by the ginger extract. In comparison ginger oil gave a higher frequency of chromosomal aberrations. It is suggested therefore, that the extract may contain substance(s) that suppress clastogenesis in the bone marrow cells of mice. Copyright (C) 2000 John Wiley and Sons, Ltd.