Introduction : Hepatitis B virus (HBV) infection is an infectious disease that maintains its importance. Recovery, inactive HBsAg (hepatitis B surface antigen) carrier state, chronic hepatitis, cirrhosis, hepatocellular carcinoma and hepatic failure are the results which may occur during the clinical course of the disease. Immune system and host-related genetic factors play an important role in the prognosis. Mannose-Binding Lectin (MBL) is known to have a function in inflammatory response. In this study, it was aimed to investigate the role of serum MBL levels during the clinical course of HBV infection. Methodology-Result : A total of 147 patients were included in the study. Serum MBL levels of chronic HBV infection group, inactive HBsAg carrier group and healthy control group were determined to be 4504 ± 3185 ng/mL, 3301 ± 2631 ng/mL and 3329 ± 2484 ng/mL; respectively. Although serum MBL levels were determined to be higher in the patients with chronic HBV infection compared to the other groups, this was not statistically significant (p=0,148). Conclusions : The role of MBL in HBV infection is not clear as to reach a clear conclusion and it seems to be an insignificant factor compared to the more important factors contributing to the infection. Again in the studies performed in recent years, a strong correlation was determined between lower levels of serum MBL and codon variants and it has been suggested that codon variants could be used as genetic marker of lower levels of serum MBL. Based on the knowledge of there was a correlation between MBL gene mutations and lower levels of serum MBL, it has been thought that MBL gene study was not cost-efficient to determine the relationship of MBL gene mutations with infections.