Ovarian cancer is the leading cause of death in gynaecological cancers. The high temperature requirement factor A3 (HtrA3) is involved in the pathogenesis of ovarian cancer. In this study we investigated whetherHtrA3 protein levels were altered in subtypes of ovarian cancer and whether HtrA3 down-regulation was associated with peritoneal metastasis. Ovarian cancer tissues from 89 patients were analyzed by immunohistochemistry. The levels of HtrA3 protein were lower in all subtypes of ovarian cancer and the lowest levels of HtrA3 were in epithelial ovarian cancer. The down-regulation of HtrA3 levels was not correlated with peritoneal metastasis of epithelial ovarian cancer.