Two cases of Meigs' syndrome in association with elevated serum CA 125 levels are reported. The significance of Meigs' syndrome lies in the fact that neither ascites nor pleural effusion is necessarily an ominous sign in women with a pelvic tumor. Although there is a strong correlation between ovarian malignancy and elevated serum CA 125 levels, several benign conditions have been found to cause a rise in CA 125 levels. It is important to remember that a pelvic neoplasm in a woman presenting with hydrothorax, ascites, and elevated CA 125 levels might be benign and that this condition can rapidly be resolved with surgical removal. Neither ultrasound examination nor computed tomography can reliably offer a preoperative diagnosis.