Abstract A recent study on the use of cancer antigen 125 (CA-125) in follow-up of patients with epithelial ovarian cancer after complete response on primary treatment is critically reviewed. As it has been suggested to refrain from CA-125 altogether, this European Society of Gynaecologic Oncology report has also reviewed possible disadvantages, even possible harm, and potentially missed opportunities when such policy would be implemented. It is concluded that indeed routine use of CA-125 does not provide patient benefit in survival or quality of life. However, there may be other reasons for monitoring CA-125, which are discussed in this review. It is noted that the lack of benefit of CA-125 monitoring has only been proven for a specific subset of ovarian cancer patients with serous histology and frequent follow-up visits including imaging and in a clinical environment where, particularly, surgery for recurrent disease and clinical studies on new second-line agents will not be considered. A special warning is issued not to stop tumor marker follow-up in other than epithelial ovarian cancers and in follow-up of patients who not have been treated with chemotherapy.