The transcription factor Oct-4 is crucial for the maintenance of cell pluripotency and is known to be expressed in embryonic stem cells, germ cells and whole embryos at various stages of development. Oct-4 regulates cell fate in a dose-dependent manner and plays a key role in germ-cell tumours. In the past, several stem-cell markers have been detected, and their role in the pathogenesis of diseases has been discussed frequently. Thus, we investigated the expression of Oct-4 comparing its occurrence in endometrium of healthy and diseased women using immunohistochemistry (IHC) and RT-PCR. IHC demonstrated Oct-4 expression in 25 of 60 sections (42%), respectively in 11 out of 25 patients (44%). Oct-4 mRNA was detected by RT-PCR in all tested samples (9 of 9) of endometrium, although the levels of expression varied. To our knowledge, this is the first study demonstrating Oct-4 expression in human endometrium.