Macaca sylvanushas a diploid chromosome number of 2n = 42. With the exception of chromosome 2 all chromosomes appear to have an identical banding pattern to most other macaque species. This chromosome has a clear band, localized immediately below the centromere; therefore, the karyotype ofM. sylvanusmore closely resembles that of the African Papionini, which also present a large clearly staining band on chromosome 2. C‐band‐ing intensely stained this band. Fluorescentin situhybridization (FISH) with human chromosome specific DNA probes to macaque chromosome 2 showed that human probe 7 was located on the whole q arm and on a small part of the p arm, immediately adjacent to the centromere; the remaining part of the p arm was hybridized by the DNA probe for human chromosome 21. It appears clear, from the hybridization pattern in the other primates and in the outgroups examined, that chromosome 7 was probably a syntenic region for many ancestral mammalian karyotypes and a single syntenic region in the ancestral karyotype of the primates. Human probe for chromosome 21 and 3 are found associated in New World primates and a wide range of mammalian species. Therefore, this syntenic association was probably ancestral for mammals and present in the ancestral primate karyotype. The translocation of 7 and 21 to form chromosome 2 ofMacaca sylvanusand all other Papionini is probably a recent trait linking all these species.