Main purpose and research question: To determine whether the true fusogen Syncytin-1 and its receptor (ASCT-2) is present in human gametes using qRT-PCR, immunoblotting and immunofluorescence. Methods: Donated oocytes and spermatozoa, originating from a fertility center in tertiary referral university hospital, underwent qRT-PCR, immunoblotting and immunofluorescence analyzes. Results: Quantitative RT-PCR of sperm samples from sperm donors showed that syncytin-1 is present in all samples, however, protein levels varied between donors. Syncytin-1 immunoreactivity predominates in the sperm head and around the equatorial segment. The receptor ASCT-2 is expressed in the acrosomal region and in the sperm tail. Moreover, ASCT-2, but not syncytin-1, is expressed in oocytes and the mRNA level increases with increasing maturity of the oocytes. Conclusions: Syncytin and its receptor are present in human gametes and localization and temporal appearance is consistent with a possible role in fusion between oocyte and sperm.