The effect of the two pesticides Dursban and Cubex on mitotic activity, mitotic abnormalities and changes in the DNA content has been investigated using Allium cepa root tip assay.  Treatment of Allium cepa root tips with the different doses of each of the two pesticides resulted in a marked effect on the frequency of mitotic phases depending on the concentration used. Each of the used pesticides induced a marked decrease in the mitotic index and gradual increase in the percentage of chromosomal abnormalities as the concentrations of each of the two pesticide increased. Chromosomal abnormalities associated with stickiness of chromosomes were the dominant abnormalities induced by these chemicals. Some of the chromosomal abnormalities, produced by these pesticides, particularly breaks, bridges and micronuclei indicate its genotoxic potential.  Image cytometric measurements demonstrated a dose-dependent effect of of the pesticide treatments on the components of mitotic cell cycle in Allium cepa root tip cells. The most evident effect appears to be the accumulation of cells in the Go/G1 phase with resultant reduction in the proportion of cells in other phases of the cycle (S  phase , G2 phase and mitosis).  Frequent use of these chemicals has a potential mutagenic effect in the environment. The results obtained in the present study indicate that the cytological examination of induced chromosomal aberrations can be used to monitor genetic damage caused by pesticides.