Multicolor fluorescence in situ hybridization, a new promising technology today, offers unparalleled capabilities for detection of nucleic acid sequences, chromosomes and genes. Owing to structural and numerical chromosomal aberrations were considered as important biological end points in genotoxic studies, chromosomal aberrations after exposure to occupational, medical, and environmental toxicants could be accurately and appropriately evaluated via this assay. Consequently, multicolor FISH-based methods could be widespread applied in human genetics, reproductive medicine, especially genetic toxicology. In this paper, the progress in regard was reviewed.