2-Chloroethanol (2-CE) has been used on grapevines to accelerate grape growth, and its metabolite, chloroacetaldehyde (CAA), accumulated in the liver and blood from rats intoxicated with 2-CE. Chronic occupational injury might be a possible reason for the 2-CE intoxication. In this study, we used the in vitro and in vivo tests to examine the genotoxicity of 2-CE and CAA. First, 2-CE did not induce chromosome aberration formation in Chinese ovary hamster cells, but CAA did induce chromosome aberration formation, especially the chromosome gap-type aberration after S9 activation. Second, 2-CE at high doses (1/2 LD₅₀), but not at low doses, induced peripheral blood micronucleus formation in mice. CAA induced micronucleus formation at low and high dosages (1/8-1/2 LD₅₀). These results indicated that CAA plays an important role in 2-CE chronic intoxication, and the genotoxic mechanisms of CAA require further study.