Abstract
Background and Objectives
Hepatitis C (HCV) infection is one of the main causes of chronic hepatitis diseases all over the world. HCV is a transfusion transmitted virus and a serious threat to general health. HCV genotyping has an important role in tracing routes of infection. This study aimed at investigating the changes in  distribution pattern of HCV genotypes among Iranian blood donors.
 
Materials and Methods
In this cross sectional study, 239 HCV confirmed blood donors from Jun. 2015 to Nov. 2017 were included. Semi nested PCR method was used for amplifying the NS5B  region of HCV genome. PCR products were sequenced and HCVgenotypes were determined by searching the sequences in Basic Local Alignment Search Tool (BLAST). Phylogenetic tree was constructed to confirm HCV genotypes. STATA 13 software was used for data analysis. 
 
Results
In 106 (44.35% ± 6.3%) out of 239 participants, HCV genotype was determined and confirmed. In phylogenetic tree, studied sequences formed three separated clusters. Genotype 3a, 1a and 1b were the common genotypes.
 
Conclusions 
It seems that molecular epidemiology of HCV infection did not change based on variability of genotypes but changes in the frequency of genotypes have been occurred as a result of replacement of genotype 1a by genotype 3a during the last decade among Iranian blood donors.