In contrast to the abundant data on hepatitis C virus (HCV) and human protein sequences, little is known about the interactions between HCV and human proteins. Hence, discovering binding domain pairs or inter-domain paths at the residue level is of general importance in the study of the interactions between HCV and human proteins. In this study, we analyzed all known binding domain pairs of HCV proteins and human liver proteins, and discovered 10 potential inter-domain paths between HCV NS5A protein and six human liver proteins. This informative result will dramatically narrow the search space of human liver proteins interacting with HCV NS5A protein. Supplementary data are available at http://hiv1.hpid.org/Pathway suppl 01.htm and http://hiv1.hpid.org/Pathway suppl 02.htm.