The serum transferrin receptor (sTfR) is a sensitive indicator of iron-deficiency erythropoiesis that is not affected by inflammation. Concentrations of this molecule are inversely correlated with body-iron stores, and increased body-iron stores are associated with an increased risk of cancer of the liver and lungs. However, an association between iron status as assessed on the basis of sTfR and prostate cancer has not been previously investigated. We measured sTfR and serum ferritin by means of an enzyme immunoassay in 27 men with newly diagnosed, untreated prostate cancer and in 72 controls. Our study population ranged in age from 38 to 78 years. The mean serum ferritin concentration in men with prostate cancer was 44.8% lower than that in men without this tumor ( P < .05). In contrast, the mean values of sTfR and sTfR/log serum ferritin were 32% and 60% higher, respectively, in men with prostate cancer than in those without this tumor ( P < .05). Differences between groups persisted after we took into account inflammation (alpha 1-acid glycoprotein > 1 g/L, C-reactive protein > 10 mg/L; P < .05). Among the entire study population and among men without inflammation, a higher percentage of subjects (29%-31%) than of controls (14%-22%) had sTfR values greater than 8 mg/L, suggestive of iron-deficiency erythropoiesis ( P < .05). The odds ratios for men with prostate cancer to have sTfR values of less than 2.9 mg/L (suggestive of increased body-iron stores) was 0, compared with 1.745 to 3.65 for the same men to have sTfR values greater than 8 mg/L. sTfR was negatively correlated with log ferritin ( r = -.422, P < .05) but did not correlate with tissue inflammation, tumor stage, or acute-phase proteins. It appears that prostate cancer is not associated with increased body-iron stores.