Abstract. We used a reverse transcription-polymerase chain reaction (RT-PCR) to obtain the genotypes of circulating hepatitis C virus (HCV) in patients from a Gastro-Hepatology Unit in the city of Salvador (Bahia State) in northeastern Brazil. Viral RNA was detected in 83 (65.4%) of 127 anti-HCV seropositive serum samples. Positivity was significantly associated with alterations in levels of aspartate aminotransferase and alanine aminotransferase (P Ͻ 0.05). Genotyping of HCV was performed by RT-PCR using genotype-specific primers from the core region: 24.1% were infected with subtype 1a, 38.6% with 1b, 3.6% with 2, 21.7% with 3a, and 12.0% with a mixed genotype. There was no difference in genotype distribution when compared with results from other Brazilian locations. Surprisingly, the high frequency of genotype 3 in Brazilian samples continues to be different from that reported around the world and warrants further investigation. Hepatitis C virus (HCV), a recently discovered virus of low viremia and immunogenicity, is unique among viruses infecting human beings in that the detection of viral RNA remains the most sensitive and reliable means of confirming infection. In addition, variations in nucleotide sequences are used to determine genotypes. [1][2][3][4][5][6][7] Since the discovery of HCV by Choo and others, 8 more than 80 genotypes have been identified. The sequences of the subgenomic regions of these genotypes differ by more than 20%. 7 The classification of HCV genotypes by Simmonds and others 7 groups HCV isolates by a phylogenetic analysis of sequence variation in part of a 222-basepair (bp) of a region coding for the nonstructural protein NS5b. They found 2 different tiers of sequence variation within this region and classified HCV into 6 types designated by Arabic numbers (1, 2, 3, etc.) and further divided into subtypes designated by letters (a, b, c, etc.). The distribution of HCV genotypes has been found to vary geographically. 9 Genotypes 1, 2, and 3 and their subtypes are distributed worldwide. In contrast, genotype 4 appears to be a pan-African type (the principal genotype in Zaire and Egypt), and genotype 5 has been found to be the principal genotype in South Africa.10,11 Genotype 6 and its variants have been found mainly in Asia. 1,9,12 In Brazil, recent studies performed in the southeastern (States of São Paulo and Rio de Janeiro) and southern (State of Rio Grande do Sul) regions demonstrated the presence of 3 HCV genotypes (1, 2, and 3). [13][14][15][16] Studies suggest that the clinical features of liver disease depend on HCV genotypes. [17][18][19][20] For instance, an association between certain genotypes and disease severity, liver cirrhosis, and primary liver cancer has been reported. 19 It is also noteworthy that the success of interferon treatment seems to be type or subtype related. 21These observations make the identification of infecting HCV genotypes from different geographic regions of great interest.The primary objective of the present study was to detect and determine the ge...