The invention relates to the X-ray crystal structure of the hepatitis C virus helicase domain. More specifically, the invention relates to crystallized complexes of HCV helicase and an oligonucleotide, to crystallizable compositions of HCV helicase and an oligonucleotide and to methods of crystallizing an HCV helicase-oligonucleotide complex. The invention further relates to a computer programmed with the structure coordinates of the HCV helicase oligonucleotide binding pocket or the HCV helicase nucleotide triphosphate pocket wherein said computer is capable of displaying a three-dimensional representation of that binding pocket.