The genotoxic effect of cadmium chloride was evaluated in chromosomes of experimental mice using in vivo and in vitro studies. In vivo the induction of micronuclei, sister chromatid exchange in mouse bone marrow and chromosomal aberrations in both somatic and germ cells was investigated. Doses 1.9, 5.7 and 7.6 mg kg(-1) body wt. (single i.p. treatment) induced a significant and dose-dependent increase in the percentage of polychromatic erythrocytes with micronuclei. Such a percentage reached 2.1% with the highest tested dose, compared with 0.57% for the control (non-treated) and 2.2% for mitomycin c as the positive control. The dose of 1.9 mg kg(-1) body wt. had no significant effect with respect to sister chromatid exchange (SCE) but the doses of 5.7 and 7.6 mg kg(-1)body wt. increased the frequency of SCEs significantly. The frequency of SCE reached 7.35 +/- 0.26 per cell after treatment with the highest tested dose, which is a less than twofold increase compared with the control frequency of 4.6 +/- 0.42 per cell. However mitomycin c induced a much higher effect (12.1 +/- 0.73). Cadmium chloride also induced a significant increase in the percentage of chromosomal aberrations in mouse bone marrow at the doses of 5.7 and 9.5 mg kg(-1) body wt. (single i.p. treatment). The effect is a function of cadmium chloride concentration. Moreover, cadmium chloride induced its maximum effect concerning the induction of chromosomal aberrations in mouse bone marrow cells 24 h after treatment, compared with 12 and 48 h. In germ cells, chromosomal aberrations were observed in mouse spermatocytes 12 days post-treatment with the dose of 5.7 mg kg(-1) body wt. Moreover, a pronounced reduction in the number of spermatocytes was observed after administration of cadmium chloride (0.9, 1.9 and 5.7 mg kg(-1) body wt.) In in vitro studies, the three tested concentrations of 10, 15 and 20 microgram ml(-1) cadmium chloride induced a statistically significant increase in the frequency of SCEs in cultured mouse spleen cells. The concentrations of 15 and 20 microgram ml(-1) also induced chromosomal aberrations in mouse spleen culture. The ability of vitamin C (l-ascorbic acid) to minimize the incidence of chromosomal aberrations induced by cadmium chloride in cultured mouse spleen cells was investigated. Vitamin C at the concentrations of 3 and 6 microgram ml(-1) significantly minimized the percentage of aberrant cells induced by cadmium chloride.