Hepatitis C virus genotype 4 (HCV-4) is very common in central Africa, prevalent in the Middle East, and is becoming increasingly frequent among southern Europeans. We have determined the complete nucleotide sequences of HCV-4f strains and investigated their phylogenetic relationships with other genotypes. We amplified the complete genome of two HCV subtype 4f strains, IFBT84 and IFBT88. The HCV-4f strains have a total of 9181 and 9304 nt, respectively, including the 5' untranslated region followed by a single open reading frame. There was no evidence of genomic recombination in the IFBT84 and IFBT88 strains. The sequences of the HCV-4f strain genomes are closer to those of HCV-1b than to genotypes 2, 3, 5 and 6. It is important to know the full-length sequences of HCV-4 subtypes in order to classify them correctly and to obtain more detailed knowledge about HCV epidemiology and sensitivity to interferon.