Background: Epithelial ovarian carcinoma produces steroid hormones that may be of prognostic importance. The steroids are mainly bound to plasma albumin and sex hormone-binding globulin. Alterations in plasma protein levels influence hormonal effects. As plasma prealbumin may reflect changes in the patient’s clinical status better than do albumin determinations, it is of interest to analyze prealbumin in patients with ovarian cancer. Methods: Fifty-one postmenopausal or oophorectomized women with epithelial cancer of the ovary were studied. Plasma prealbumin was analyzed prior to and during chemotherapy. Tumor volumes were evaluated and blood samples were drawn for prealbumin analysis on four occasions at monthly intervals. Plasma levels were compared with one control group of postmenopausal women, one group of fertile women in the follicular phase of the menstrual cycle, and one control group of postmenopausal women with nongynecologic disseminated malignant disease. Results: Prealbumin conentrations are lower in women with carcinoma of the ovary than in postmenopausal controls and the levels correlate inversely to tumor volume. Prealbumin concentrations are decreased in the large tumor group, advanced tumor stage group and in the control group with nongynecologic disseminated malignant disease. During chemotherapy, plasma prealbumin increases concomitantly with the reduction of tumor volume. Initial plasma prealbumin concentration seems to have prognostic importance. Conclusions: Prealbumin may be a sensitive indicator of disturbances in protein metabolism. It may reflect changes in the patient’s clinical status better than do albumin determinations. Prealbumin concentration seems to have a prognostic importance in women with epithelial ovarian carcinoma. Condensation: Prealbumin is studied in women with epithelial ovarian carcinoma prior to and during chemotherapy, and is found to vary inversely with changes in tumor volume.