Pendimethalin is an extensively used dinitroaniline herbicide. The half-life of pendimethalin in soil can be long, and accumulation of this herbicide in the environment is probable. Therefore, we investigated the influence of pendimethalin (0.033, 0.066, 0.099, 0.132 and 0.264 g/L) on cell division during short-term treatment (24 and 48 hours) using Allium test. We observed inhibition of root elongation after 48 hours of incubation with pendimethalin. This effect was caused by the inhibition of mitoses varying from 1/3 to 1/2 in the case of 0.033, 0.066 and 0.099 g/L of pendimethalin, and almost complete restriction of mitoses under higher concentrations. Pendimethalin caused mitotic disturbances (c-metaphases, anaphasal and telophasal chromosome bridges, multipolar anaphases) and interphase abnormalities (micronuclei, multinuclear cells). This effect was irreversible during a 48-hour postincubation in water. Mitotic disturbances were caused by abnormalities in the organization of the tubulin cytoskeleton. Results suggest that even small amounts of pendimethalin can be a danger for dividing cells and embryos.