Plasma retinol-binding protein (RBP), prealbumin, vitamin A (total) and beta-carotene levels were studied in premenopausal women with node-positive breast carcinoma receiving adjuvant chemotherapy. Plasma levels were measured prior to chemotherapy and at monthly intervals during the chemotherapy course. The results showed that significantly lower RBP levels during the course of the study were associated with early tumor recurrence. Patients who maintained a disease-free status for 24 months or longer had significantly higher plasma RBP levels than those who had tumor metastasis at distant sites within 24 months after beginning chemotherapy. RBP levels were not associated with adjuvant chemotherapy (CMF)-induced hormonal changes (amenorrhea vs. no amenorrhea), or family history of breast cancer. In contrast, breast cancer patients with a prior history of benign breast disease had significantly lower RBP levels than did healthy, premenopausal women. Reduced RBP levels in these patients are due to neither an inadequate dietary intake of beta-carotene, nor to severe protein malnutrition.