Immunohistochemical staining showed that the expression of CA125was negative in all fibroma/fibrothecoma tissues, but positive in all EOC tissues, and the immunoreactivity for CA125 was positively correlated with serum CA125 level in the EOC patients (P = .005).The elevated serum CA125 level in ovarian fibroma/fibrothecoma is nontumor originated and occurs more frequently in those with larger size tumor or Meigs syndrome.