It is well known that chromosome in situ hybridization allows the unequivocal identification of targeted human somatic chromosomes. Different fluorescent in situ hybridization (FISH) techniques have been developed throughout the years and, following the mitotic studies, meiotic analyses have been performed using these different techniques. The introduction of M-FISH techniques to the analysis of meiotic cells has allowed the study of meiotic processes for every individual human chromosome. In this paper, we review the different FISH and M-FISH techniques that have been used on human meiotic cells in both men and women. Copyright © 2006 S. Karger AG.