Rapid allograft infection complicates liver transplantation (LT) in patients with hepatitis C virus (HCV). Pegylated interferon‐α and ribavirin therapy after LT has significant toxicity and limited efficacy. The effect of a human monoclonal antibody targeting the HCV E2 glycoprotein (MBL‐HCV1) on viral clearance was examined in a randomized, double‐blind, placebo‐controlled pilot study in patients infected with HCV genotype 1a undergoing LT. Subjects received 11 infusions of 50 mg/kg MBL‐HCV1 (n = 6) or placebo (n = 5) intravenously with three infusions on day of transplant, a single infusion on days 1 through 7 and one infusion on day 14 after LT. MBL‐HCV1 was well‐tolerated and reduced viral load for a period ranging from 7 to 28 days. Median change in viral load (log10 IU/mL) from baseline was significantly greater (p = 0.02) for the antibody‐treated group (range −3.07 to −3.34) compared to placebo group (range −0.331 to −1.01) on days 3 through 6 posttransplant. MBL‐HCV1 treatment significantly delayed median time to viral rebound compared to placebo treatment (18.7 days vs. 2.4 days, p < 0.001). As with other HCV monotherapies, antibody‐treated subjects had resistance‐associated variants at the time of viral rebound. A combination study of MBL‐HCV1 with a direct‐acting antiviral is underway.