Abstract. 15-Deoxy-∆ 12,14 -prostaglandin J 2 (15d-PGJ 2 ), a peroxisome proliferator-activated receptor γ ligand, has been reported to have antiproliferative activity in certain types of cancer. The purpose of this study was to elucidate the effect of 15d-PGJ 2 on endometrial cancer cells, as well as the mechanism of action. Endometrial cancer-derived cells (HHUA, Ishikawa and HEC-59) were treated with various concentrations of 15d-PGJ 2 , and its effects on cell growth, the cell cycle and apoptosis were investigated in vitro. Using cDNA microarrays, some potential targets of this drug were identified. All endometrial cancer cell lines were sensitive to the growth-inhibitory effect of 15d-PGJ 2 . Cell cycle arrest at the G2/M phase of the cell cycle and induction of apoptosis were observed. Concerning the gene expression changes induced by 15d-PGJ 2 treatment, the upregulation of aldo-keto reductase family 1 member C3 (AKR1C3) and the downregulation of anterior gradient homolog 3 (AGR3) and nitric oxide synthase 2A (NOS2A) were confirmed using western blot analysis in all the cell lines examined. These results suggest that 15d-PGJ 2 may be a novel therapeutic option for the treatment of endometrial cancer.