The karyotype of the red brocket deer, Mazama americana is described. Skin biopsies of a pair and their young male offspring were cultured for the study of centromeric heterochromatin and G-bands. The chromosome number of father and son was 2n=50; that of the doe was 2n=49 in all metaphases examined. In the doe, one of smallest acrocentric elements was missing and is apparently translocated to the end of the long arm of one submetacentric chromosome No. 4. This translocation of the non-Robertsonian type has not been described in Artiodactyla before, moreover, the chromosome number differs from that reported to be as 68 in one single specimen reported previously.