Intrauterine transmission of hepatitis B virus (HBV) is the main cause of the high prevalence of HBV in endemic areas; however, the mechanisms underlying intrauterine transmission of HBV remain unknown. To explore the role of mannose-binding lectin (MBL), a pattern recognition molecule of the innate immune system, in intrauterine transmission of HBV, we determined MBL levels using an enzyme-linked immunosorbent assay (ELISA) in cord serum of 7 intrauterine-infected neonates and 30 non-infected neonates born to HBV-positive mothers, and 30 control neonates born to HBV-negative mothers. We observed significant differences in cord serum MBL levels among the three groups (P < 0.001). Non-infected neonates had significantly higher MBL levels than controls (P < 0.001), and intrauterine-infected neonates had significantly lower serum MBL levels than non-infected neonates (P < 0.001). However, serum MBL levels were not significantly different between intrauterine-infected neonates and controls (P = 0.800). Our results indicate that maternal HBV infection induces an increase in fetal MBL levels and the absence of this increase is possibly associated with intrauterine transmission of HBV, suggesting that MBL plays a role in intrauterine transmission of HBV.