The wealth of human genome sequence information now available, coupled with technological advances in robotics, nanotechnology, mass spectrometry, and information systems, has given rise to a method of scientific inquiry known as functional genomics. By using these technologies to survey gene expression and protein production on a near global scale, the goal of functional genomics is to assign biological function to genes with currently unknown roles in physiology. This approach carries particular appeal in disease research, where it can uncover the function of previously unknown genes and molecular pathways that are directly involved in disease progression. With this knowledge may come improved diagnostic techniques, prognostic capabilities, and novel therapeutic approaches. In this regard, the continuing evolution of proteomic technologies has resulted in an increasingly greater impact of proteome studies in many areas of research and hepatology is no exception. Our laboratory has been extremely active in this area, applying both genomic and proteomic technologies to the analysis of virus-host interactions in several systems, including the study of hepatitis C virus (HCV) infection and HCV-associated liver disease. Since proteomic technologies are foreign to many hepatologists (and to almost everyone else), this article will provide an overview of proteomic methods and technologies and describe how they are being used to study liver function and disease.