Flow cytometric techniques are described to quantify micronucleus (MN) induction in cell cultures and human lymphocytes. The advantages and disadvantages of these techniques are discussed. Because a suspension of nuclei and MN has to be prepared for flow cytometric measurements, care has to be taken to avoid unspecific debris that can influence the results. Using additional flow cytometric parameters, most of the unspecific particles in the suspension can, however, be gated out. Apoptotic cells and apoptotic bodies can overlap the MN during measurement, it is, therefore, proposed not to use the technique if apoptosis is induced by the respective treatment. Advantages of the automated flow cytometric techniques are that results can be obtained in short time intervals, the frequency of MN and the DNA distribution of MN can be measured simultaneously and flow sorting can be used for a further analysis of MN using other techniques.