We investigated the clinical significance of platelet-derived endothelial cell growth factor (PD-ECGF) as measured by enzyme-linked immunosorbent assay in primary epithelial ovarian cancers (EOC), finding amounts to be significantly greater in cancers than in normal ovarian tissue (p<0.01). PD-ECGF was significantly more abundant in stages III and IV than in lower stages (p<0.05), and also was high in tumors with macroscopically evident metastases in the peritoneal cavity (p<0.05), or pelvic (p<0.01) or paraaortic (p<0.01) lymph node metastases. Further, PD-ECGF was significantly lower in mucinous than in serous adenocarcinomas (p<0.05). No significant correlation was seen between PD-ECGF and histologic grade, maximum intraperitoneal metastatic tumor diameter (<2 vs.>2 cm), or presence of demonstrable malignant cells in peritoneal fluid. In stage III disease, PD-ECGF exhibited significant correlation with recurrence (p<0.05). Our data suggested that results of PD-ECGF assays in primary tumors can predict progression and recurrence of EOC.