Occult hepatitis C virus (HCV) infection (OCI) is the detection of HCV RNA in either liver tissue or peripheral blood mononuclear cells (PBMC) despite repeatedly undetectable levels of HCV RNA in serum.1 From a clinical perspective, OCI has been linked to liver disease of unknown origin (anti-HCV negative, serum HCV RNA negative), as well as to persistence of abnormal liver tests in some patients who achieve spontaneous or treatment-induced HCV RNA clearance from serum (anti-HCV positive, serum HCV RNA negative).