Branched‑chain amino acids (BCAAs) and trace element deficiencies are associated with poor prognosis in hepatitis C virus (HCV)‑infected patients. The aim of this study was to investigate the effects of BCAA and zinc‑enriched supplementation on prognostic factors in HCV‑infected patients. Fifty‑three HCV‑infected patients were enrolled in this multicenter randomized controlled trial. The patients were assigned to either the placebo (n=27) or supplement group (n=26; 6,400 mg/day BCAAs and 10 mg/day zinc) and were followed up for 60 days. Primary outcomes were prognostic factors for chronic liver disease, including the serum BCAA‑to‑tyrosine ratio (BTR), zinc levels and α‑fetoprotein (AFP) levels. There were no significant differences in any of the prognostic factors between the placebo and supplement groups at baseline. In the supplement group, the BTR and zinc levels were significantly increased compared with the placebo group (BTR: 5.14 ± 1.59 vs. 4.23 ± 1.14, P=0.0290; zinc: 76 ± 11 vs. 68 ± 11 µg/dl, P=0.0497). No significant differences were observed in AFP levels between the groups in the whole analysis. However, a stratification analysis showed a significant reduction in ΔAFP levels in the supplement group, with elevated AFP levels compared with the other groups (‑2.72 ± 3.45 ng/ml, P=0.0079). It was demonstrated that BCAA and zinc‑enriched supplementation increased the BTR and zinc levels in the HCV‑infected patients. Furthermore, the supplementation reduced the serum AFP levels in patients who had elevated serum AFP levels at baseline. Thus, BCAA and zinc‑enriched supplementation may prolong the survival of HCV‑infected patients by improving amino acid imbalance and zinc deficiency, and by partly downregulating AFP.