A new highly repeated DNA fragment isolated from Macaca fascicularis (MFASAT) is described. Our findings obtained by sequencing, Southern blot analysis, and fluorescent in situ hybridization (FISH) on metaphasic chromosomes strongly suggest that MFASAT can be considered as a member of the alphoid DNA family characteristic of Old World monkeys. The chromosomal localization of MFASAT, obtained by FISH, showed that this alphoid DNA is present in the peri-centromeric area of all the chromosomes. MFASAT showed a high degree of conservation when compared, by sequence alignment, to other Macaca species and Papio papio as expected for species with considerable genome conservation. A low degree of homology has been found comparing M. fascicularis alphoid DNA with a more distantly related Cercopithecidae species such as Cercopithecus aethiops.