The potential of growth, invasion and metastasis of ovarian cancer cells associated with neovascularization, and the expression of platelet-derived endothelial growth factor (PD-ECGF) and its mRNA in ovarian cancers were determined. The relationship between their expression and histopathological types and clinical stages of ovarian cancers was also analyzed. The levels of PD-ECGF and its mRNA were higher in ovarian cancers than in normal ovaries. Furthermore, some endometrioid carcinomas and serous cystadenocarcinomas of the ovary and some ovarian cancers in stages III and IV expressed remarkably high levels of PD-ECGF and its mRNA. Therefore, in some ovarian cancers, PD-ECGF might be related to advanced stages of ovarian cancers associated with neovascularization.