A method of chromosome painting on human sperm chromosomes using fluor
escent in situ hybridization (FISH) is introduced. Sperm chromosome sl
ides were prepared after in vitro fertilization of hamster eggs with h
uman spermatozoa. The slides were treated by RNase A before FISH. Chro
mosome 4 was clearly and specifically painted in a majority of sperm-d
erived metaphase plates after an application of whole chromosome paint
ing DNA probes of this chromosome. This is the first report of success
ful painting on human sperm chromosomes.