Myostatin is a member of the transforming growth factor (TGF)- superfamily, known for its ability to inhibit muscle growth. It can also regulate metabolism and glucose uptake in a number of tissues. To determine the mechanism of myostatin’s effect on glucose uptake we evaluated it’s actions using choriocarcinoma cell lines that are widely used as models for placental cells. Protein and mRNA were determined using immunoblotting and RT-PCR/PCR respectively. Glucose uptake was assessed by uptake of radiolabeled deoxyglucose in-vitro. All Choriocarcinoma cell lines tested i.e. BeWo, JEG and JAr are used as models of placental cells and all expressed myostatin protein and mRNA. Treatment of BeWo cells with myostatin resulted in inhibition of glucose uptake in a concentration-dependent manner (P<0.01). At all concentrations tested, follistatin, a functional inhibitor of myostatin, completely blocked the inhibitory effect of myostatin (40nM) on glucose uptake by BeWo cells (0.4nM, P<0.05). Follistatin treatment alone also increased glucose uptake (0.4nM and 4nM, P<0.001; 40nM, P<0.05). As BeWo cells proliferated and greater cell densities were achieved, glucose uptake declined irrespective of treatment. Myostatin treatment of BeWo cells did not alter the levels of myostatin receptor, ActRII A/B proteins. The levels of glucose transport proteins also remained unaltered in BeWo cells with myostatin treatment. This study has shown that myostatin specifically inhibits glucose uptake into BeWo cells, suggesting that locally produced myostatin may control glucose metabolism within the placenta.