['Angiogenesis is a critical factor in the progression of solid tumors and metastasis. The aim of this study was to characterise the roles of angiogenic and anti-angiogenic factors on ovarian cancer.', 'The expression levels of vascular endothelial growth factor (VEGF, angiogenic factor) and pigment epithelial growth factor (PEDF, anti-angiogenic factor) were measured by real-time polymerase chain reaction and Western blotting in ovarian tumors. Microvessel density (MVD) was evaluated by the total microvessel length in high-power field of tumor tissue preparations.', 'MVD correlated with tumor malignancy. The tissues with the highest expression levels of VEGF (VEGF-H) were malignant tumors. The VEGF expression levels in some malignant tumors (VEGF-L) were as low as that in benign tumors. Therefore, the expression of PEDF was examined. The PEDF expression levels in VEGF-L malignant tumors were significantly lower than those in benign tumors. On the other hand, the PEDF expression levels in VEGF-H malignant tumor tissues were not significantly different from those in benign tumors.'] Is the reduction in pigment epithelium-derived factor a sign of malignancy in ovarian cancer expressing low-level of vascular endothelial growth factor?