Leptin, a secreted protein of the ob gene by white adipose tissue, plays an important role in the regulation of food intake and energy consumption in the brain and acts as a potential growth stimulator in normal and neoplastic breast cancer cells. However, a potential role of leptin as an endocrine regulator is unknown in ovarian cancer. In the present study, we investigated the expression of leptin receptors in immortalized ovarian surface epithelium (IOSE) and ovarian cancer cell lines, and potential effect of leptin on the cell growth and activation of mitogen-activated protein kinases (MAPKs) in the BG-1 ovarian cancer cell line. Both short and long isoforms of leptin receptors are expressed in IOSE-80PC (a post-crisis line), BG-1, OVCAR-3, and SKOV-3 cells. In addition, treatment with leptin resulted in the growth stimulation of BG-1 cells, an activation of ERK1/2 and inhibition of constitutive phosphorylation of p38 MAPK. These results suggest that further studies are necessary to validate whether leptin may be a potential regulator for ovarian cancer.