Of the various classes of human genetic disorders, Superovulated ICR female mice were administered aneuploidy is the most prevalent. Besides its associ-0, 50, 100, or 150 mg/kg TBZ by intraperitoneal ation with maternal age and its predominant origin injection. The frequencies and percentages of hyduring maternal meiosis I, little is known about the perploid oocytes were 0/472 (0), 2/410 (0.5), 6/ etiology of aneuploidy. Although various classes of 478 (1.3), and 3/427 (0.7) for control, 50, 100, chemicals have been shown to induce aneuploidy and 150 mg/kg TBZ, respectively. The difference in experimental systems, there is no definitive evi-between controls and the 100 mg/kg dose was dence for the role of chemically induced aneuploidy statistically significant. Also, the proportions of ovuand adverse human health effects, particularly germ latory mice and the number of oocytes collected cell effects. Thus, it is important to understand the per ovulatory female were reduced in the TBZ groups potential of chemicals for inducing aneuploidy in relative to controls. Based on these results, we congerm cells. There are conflicting data in the litera-clude that TBZ induces a small, but significant increase ture about the ability of thiabendazole (TBZ) to in-in the frequency of aneuploid oocytes at toxic doses duce aneuploidy; therefore, we investigated the po-that also impair ovulation.