Fe status is difficult to assess in the presence of infections. To assess the role of the acute- phase response (APR) and other predictors of serum ferritin and transferrin receptor, we conducted a cross-sectional study among pulmonary tuberculosis (PTB) patients in Mwanza, Tanzania. The acute- (serum ferritin) phase protein, serum α1-antichymotrypsin (ACT) and serum ferritin and serum soluble transferrin receptor (sTfR) were measured, and data on smoking, soil and alcohol intake, and infection status were collected. Linear regression analysis was used to assess the role of elevated serum ACT and other predictors of serum ferritin and serum sTfR. Of 655 patients, 81·2 % were sputum positive (PTB+) and 47·2 % HIV+. Mean serum ACT was 0·72 g/l, with 91·1 % above 0·4 g/l. Among females and males, respectively, geometric mean serum ferritin was 140·9 and 269·1 μg/l (P < 0·001), and mean serum sTfR 4·3 and 3·8 mg/l (P < 0·001). Serum sTfR was increased 0·5 mg/l and log serum ferritin increased linearly with serum ACT >0·4 g/l. PTB+ and HIV infection, alcohol drinking and smoking were the positive predictors of serum ferritin, and female sex, soil eating, Schistosoma mansoni and hookworm infection were the negative predictors. Similarly, smoking and HIV infection were the negative predictors of serum sTfR, and female sex, soil eating and PTB+ were the positive predictors. Serum ferritin and serum sTfR are affected by the APR, but may still provide information about Fe status. It may be possible to develop algorithms, based on the markers of the APR and Fe status, to assess the Fe status among the patients with tuberculosis or other infections eliciting an APR.