Endoglycosidic heparanase degrades heparan sulfate glycosaminoglycans, and may be important in cancer invasion and metastasis, although its expression in human epithelial ovarian cancer has not been characterized. Heparanase association with clinicopathological features regarding prognostic significance was examined in patients presenting with epithelial ovarian tumor. Gene expression of heparanase was assessed by reverse transcription-PCR in 5 borderline and 31 malignant epithelial ovarian tumors. Heparanase mRNA expression was high in 16 of 31 malignant epithelial ovarian tumors. In contrast, there was no specimen presenting high heparanase mRNA expression in five borderline epithelial ovarian tumors. Heparanase expression was significantly higher in tumors with massive ascites and high grade (p=0.049 and p=0.006, respectively). There was no association between heparanase expression and patient outcome. These findings provide evidence that heparanase expression may be associated with a high grade phenotype in this class of neoplasm.