Human ADAM-19 is a newly identified member of ADAM family, and is highly expressed in human placenta. But its functions in human trophoblast cells invasion have yet to be elucidated. A well-accepted human trophoblast cell model, NPC cell line, was used as in vitro model to investigate the influence of hADAM-19 on cell invasion in human trophoblasts. The regulation of hADAM-19 expression by transforming growth factor β1 (TGF-β1) was investigated by RT-PCR and Western blotting. It was shown that over-expression of hADAM-19 in NPC cells led to down-regulation of MMP-9, MMP-2 mRNA expression and decrease in cell invasion. In NPC cells, the expression of hADAM-19 was significantly up-regulated by TGF-β1 in a dose-dependent manner. The data indicated that there existed paracrine regulation of ADAM-19 in human placenta. ADAM-19 was involved in invasion-inhibiting regulation of human trophoblast cells, and it may function, at least in part, through coordination with various MMPs.