Epithelial ovarian cancer is an aggressive malignancy with a generally poor outcome. To improve survival, novel therapeutic strategies for this disease are needed and require elucidation of the biological events that underlie transformation and tumor growth. Vascular permeability factor (VPF), also known as vascular endothelial growth factor, is a homodimeric glycoprotein that acts on vascular endothelium as a potent permeability-inducing agent and mitogen. The present study demonstrates for the first time the constitutive gene expression of VPF in normal and neoplastic human ovaries. Abundant levels of VPF have been identified by an immunoassay in the ascites of patients with epithelial ovarian cancer (K-T. Yeo et al., Cancer Res., 53: 2912-2918, 1993). We have identified the malignant epithelium as one source of VPF in the ascites. Reverse transcription-polymerase chain reaction has demonstrated the expression of the two secreted isoforms, VPF121 and VPF165, in normal and neoplastic ovaries. Western blotting and an endothelial cell proliferation assay confirmed secretion of a biologically active product. VPF may be an important mediator of ascites formation and tumor metastasis observed in neoplastic conditions of the ovary.