Serial CA 125 levels during chemotherapy for metastatic or recurrent endometrial cancer. The purpose of this study was to evaluate the role of serial CA 125 in monitoring disease status during chemotherapy in women with metastatic or recurrent endometrial cancer. CA 125 was measured in 21 women receiving cisplatin, etoposide, and Adriamycin for a total of 275 courses of chemotherapy (median eight). Eight of ten patients had elevated pre-therapy CA 125 levels (median 233 U/mL). CA 125 became and/or remained negative in all 20 women with responding or stable disease and was elevated in all nine patients who relapsed. The median level at the time of relapse was 56 U/mL. Levels were elevated before clinical relapse in five of nine patients (56%). Serial CA 125 may aid in the management of women receiving chemotherapy for advanced or recurrent endometrial cancer. 