For the first time a case of X-trisomy (XXX-gonosome aberration) in a Fleckvieh-heifer is reported. Cytogenetic examination of leukocytes and tissue cultures from the skin of this animal gave in 100% of the examined cells the karyotype 2N = 61, XXX. Except for a pronounced kyphosis of the lumbar column, there were no clinical symptoms. Sex organs and sexual function showed nothing peculiar. The teratogram from the father of the XXX-heifer showed genetical connections in the etiology of kyphosis. It seems also that in the family line an inherent genetical disposition to meiotic disturbances, in the sense of non-disjunction, exist because recently a case of an XXY-gonosome abnormality with bilateral testicle hypoplasia (bovine hypogonadism) was registered in the second generation of the father’s bree