Doxorubicine is an anthracyclin used widely in medical oncology. The purpose of this investigation was to evaluate the genotoxic and clastogenic effects of this substance through the cytokinesis-block micronucleus assay. This short-term mutagenicity assay is of easy realization and quick interpretation. It has enabled the demonstration of a significant decrease, after exposure of cells to doxorubicin, of the rate of micronucleated cells (average = 10.8 +/- 5.7 micronucleus versus 31.9 +/- 11.5 after exposure, p < 0.0001) and chromosomic aberrations (1 aberration for the control culture versus 17 since the first dose, p < 0.001). At the end of this study, the cytokinesis-block micronucleus assay represents a reliable test to study and evaluate the genotoxic power of some substances.