Objective To determine whether human embryonic stem cell (hES) line H1 can express the germ cell differentiation associated genes in vitro. Methods The characteristics of H1 was analyzed with the expression of alkaline phosphatase, immunologic markers and pluripotency markers. Giemsa staining was used to indicate the karyotype of H1. The expression of germ cell differentiation associated genes on H1 was detected by RT-PCR. The normal human testis and human embryonic fibroblast cell line HFF-1 served as the positive and negative controls respectively. Results H1 remained the normal karyotypes 46 and XY and maintained the proliferation in an undifferentiated state. H1 expressed high levels of alkaline phosphatase(AP). However, unlike mouse embryonic stem cells (mES), H1 did not express SSEA-1(stagespecific embryonic antigen1), but expressed the SSEA4, TRA-160, TRA-181 and OCT4. In addition, H1 expressed OCT4 and NANOG, which presented the specific gene of pluripotency and selfrenewal. Premeiotic germ cellspecific genes were expressed in H1, including STELLAR (STELLArelated)，DAZL(deleted in azoospermialike)，PUM1 (PUMILIO 1)，PUM2 (PUMILIO 2)，FRAGILIS and GDF3(growth and differentiation factor 3). H1 did not express the germ cellspecific genes of meiotic and postmeiotic differentiation, including the meiosis initiating gene STRA8(stimulated by retinoic acid gene 8), meiosis specific gene SCP1(synaptonemal complex protein 1), germ cell mature differentiation gene VASA, PGCs (primordial germ cells) specific gene BLIMP-1