Endometriosis is generally assumed to be a benign disease, but it shares many characteristics with malignancy, such as invasive and unrestrained growth and a tendency to metastasize and recur. Although not yet fully delineated, there is a relationship between endometriosis and specific types of epithelial ovarian carcinomas (EOC). A case of an endometrioid ovarian carcinoma in a previously hysterectomized postmenopausal woman, associated with diffuse pulmonary endometriosis is presented. After series of diagnostic and therapeutic procedures, a patient was successfully treated with surgery, chemotherapy, and resection of the suspicious pulmonary lesions which led the authors to a final diagnosis. Most likely such patients with endometriosis-associated ovarian cancers represent different types of patients than traditional ones with ovarian cancer and may require a different therapeutic approach.