The aim of the study was to assess the expression of cyclooxygenases (COX)-2 in nonepithelial ovarian malignancies.COX-2 immunohistochemical staining was performed on newly prepared deparaffinized slides from formalin-fixed, paraffin-embedded archival tissue blocks of unselected nonepithelial ovarian malignancies diagnosed between January 1993 and October 2009 after reconfirmation of the diagnosis. Staining was assessed according to intensity of staining and the proportion of stained cells. Staining of more than 10% of the cells was considered positive.During the study period, 26 histologically proven nonepithelial ovarian malignancies were diagnosed. Of them, 16 were granulosa cell tumors and 10 were germ cell tumors (4 dysgerminomas and 6 immature teratomas). Five (31.2%) granulosa cell tumors had positive immunohistochemical COX-2 staining. Positive staining was observed only in 1 immature teratoma and in none of the dysgerminomas.Our data seem to indicate that COX-2 expression by immunohistochemical methods is not frequent in nonepithelial ovarian malignancies.