An overall anti-hepatitis C virus (HCV) prevalence of 6.7% was found in a sero-epidemiological study carried out in the town of Conakry (Guinea Conakry, West Central Africa) on 1421 subjects who were either blood donors, pregnant women or in- and outpatients receiving treatment for conditions other than liver disease. Seven HCV isolates from a subsample of 73 sterile sera from this population were studied for genetic characterization and classification. The 5'NCR was analysed by the Line Probe Assay. This method assigned the isolates to genotype 2. Analysis of the 5'NCR sequences alone was unable to give a more accurate classification. Comparison of NS5b region sequences (nucleotides 7575-8196), from Guinea isolates and genotype 2 database sequences, showed evolutionary distances in the range 0.15-0.26. There was a high level of subtype heterogeneity among the genotype 2 Guinea HCV isolates. Four of the subtypes were possibly new.