Every year, in the European countries more than 2 million tons of pesticides are released into the environment. More than 60% of those substances appear to be herbicides. Due to extensive production and application of this chemical their putative detrimental effect on life should be known and minimized. In this study we applied the comet assay on blood and 4 mouse organs (kidney, liver, bone marrow, and spleen) to evaluate possible genome damage caused by two pesticide formulations (Bravo and Gesaprim) containing alachlor and atrazine as active ingredients. Five male CBA mice were assigned to each of 4 treatment groups and control group. Bravo and Gesaprim were injected intraperitoneally once. Two different doses of Bravo were used: 0.031 ml/kg and 0.021 microl/kg, so that doses of alachlor mice received within the pesticide formulation given were 15 mg/kg and 0.01 mg/kg. Also Gesaprim was given at two different doses: 1.08 ml/kg and 0.07 microl/kg so that the doses of atrazine contained within the pesticide formulation given were 540 mg/kg and 3.5 x 10(-2) mg/kg. Mice were sacrificed 24 hours after treatment. Alkaline comet assay on the blood samples, kidney, liver, bone marrow and spleen was performed. Statistically significant (p<0.01) increase of tail length for all 5 tissues examined in mice treated with both Bravo and Gesaprim compared to the control was found. For both pesticides DNA of kidney and liver showed largest increase in migration. Also, distribution of tail length values for Bravo and Gesaprim for all mouse tissues examined showed a shift to the right when compared to the controls.