A disintegrin and metalloproteinases (ADAMs) are members of the metzincin family of zinc-dependent metalloproteinases that play pivotal roles in the proteolytic degradation of the extracellular matrix for cell invasion. Few studies have investigated the ADAM subtypes that are expressed in first trimester trophoblast cells. The purpose of this study was to elucidate the differential expression profiles of ADAMs between first trimester villous trophoblast cells (VTs) and extravillous trophoblast cells (EVTs). We isolated EVTs from explanted human first trimester chorionic villi and investigated the mRNA expression levels of five members of the ADAM family (ADAMTS1, ADAMTS2, ADAM10, ADAM12, and ADAM17) using real-time PCR. Chorionic villous tips were defined as first trimester VTs. Of the differentially expressed ADAM genes between first trimester VTs and EVTs, ADAMTS1 was expressed at a significantly higher level in EVTs than in VTs. In contrast, both ADAM10 and ADAM12 were expressed at significantly higher levels in VTs than in EVTs. No differences were found in the mRNA levels of ADAMTS2 and ADAM17 between the two cell types. Moreover, we demonstrated that in VTs, the expression level of ADAM12 was significantly downregulated in the late first trimester (10-13 gestational weeks) compared to the middle first trimester (7-8 weeks). These results suggest that first trimester trophoblast cells express ADAM genes in cell type- and gestational age-dependent manners. Our data provide additional insight into the functions of ADAMs in the human placenta.