The Oct-4 (octamer-4), a member of the POU family transcription factor, is expressed in early mouseembryogenesis and in pluripotent embryonic stem (ES) lines. Oct-4 expression is thought to remain confined tothe germline after gastrulation in the embryo. Therefore, the study was designed to, study the location of Oct-4protein in the ovaries, placenta and testis of Korean native cattle (Hanwoo). Expression of Oct-4 mRNA in theovaries and placenta of bovine was confirmed by RT-PCR and immunohistochemical analysis. Oct-4 wasexpressed in granulosa, thecal cells irrespective of the shape and size of follicles and endometerium of Koreannative cattle (Hanwoo). Expression of Oct-4 was profound in all the tissues of Korean native cattle (Hanwoo)suggestung their role in them. Oct-4 localization and expression could contribute to further developmentalstudies in Korean native cattle (Hanwoo).