Objective: Oct 3/4 (Octamer 3/4), a member of POU family has been considered as an important stem cell marker and essential transcription factor during human embryogenesis. In recent years, there have also been reports on presence of Oct 3/4 in differentiated benign and malignant human cells. The objective of this study was to investigate the transcription and the protein expression of Oct 3/4 isoforms in ovarian cancer. Materials and Methods: 33 ovarian cancer specimens studied. The transcription of Oct 3/4 was analyzed using RT-PCR approach associated with restriction digestion analysis. Oct 3/4 protein expression was studied by immunohistochemistry Results: We detected expression of type 1 of Oct 3/4 as well as protein expression with nuclear localization of Oct 3/4 isoform 1. The stem cell markers CD44 also were detected in Oct 3/4 immunopositive cells Conclusion: Our results indicate that only the nuclear isoform 1 of Oct 3/4 is present in ovarian cancer. The malignant cells, which are immunopositive for variant 1 of Oct 3/4, also expressed another stem cell marker CD44 supporting that variant 1 of Oct 3/4 is a pluripotency marker.