Ovarian cancer is a major cause of lethality from gynecological malignancies, and there is a lack of reliable and specific serum markers for this disease. Eicosanoid-related enzymes have previously been implicated in the pathogenesis of various types of cancer, but little is known about the relevance of lipoxygenase isoforms in ovarian cancer and the results on cyclooxygenases are conflicting. For this study, we quantified the expression of eicosanoid-related enzymes (cyclooxygenase-1 and cyclooxygenase-2, 15-lipoxygenase-1 and lipoxygenase-2, 5-lipoxygenase) in normal and malignant human ovarian tissue by real-time polymerase chain reaction and found a 22-fold elevated expression of 15-lipoxygenase-2 in malignant specimens when compared with normal ovarian tissue (P=0.001). In ovarian carcinoma metastases, expression of the enzyme was also augmented (20-fold upregulation, P=0.004). For 15-lipoxygenase-1 and cyclooxygenase-2, we did not observe differential expression, but there was a trend for increased steady-state concentrations of cyclooxygenase-1 (P=0.1 for ovarian carcinoma, P=0.011 for metastases) and 5-lipoxygenase (P=0.1 for ovarian carcinoma, P=0.018 for metastases, respectively). These data indicate that expression of 15-lipoxygenase-2 mRNA is strongly augmented during ovarian carcinogenesis and that the enzyme may constitute a suitable candidate as a tumor marker.