Antibody responses to the GOR autoepitope are frequently detected among anti-hepatitis C virus (anti-HCV)-positive patients with chronic hepatitis. Sera from 110 anti-HCV-negative patients with occult HCV infection, as diagnosed by detection of HCV RNA in hepatic tissue, were investigated for GOR antibody reactivity. A positive test for anti-GOR immunoglobulin G (IgG) was found for 22 (20%) of them. The frequency and titers of anti-GOR IgG were significantly lower than those in chronic hepatitis C patients (70/110, 63.6%; P < 0.001). Anti-GOR IgG was not detected in any of the 120 patients with HCV-unrelated liver disease. The anti-GOR IgG assay showed specificity and sensitivity values of 100% and 20%, respectively, among the sera from patients with occult HCV infection; the positive and negative predictive values were 100% and 44.3%, respectively. None of the clinical, laboratory, or histological characteristics of the patients with occult HCV infection were different according to GOR antibody status, except that the percentage of HCV RNA-positive hepatocytes was significantly greater (P = 0.042) in patients with occult HCV infection who tested positive for anti-GOR IgG. In conclusion, serum anti-GOR IgG is present in patients with occult HCV infection, despite a lack of detectable HCV-specific antibodies as determined by commercial tests. Testing for anti-GOR IgG in patients in whom HCV RNA is not detected in their sera may help with the identification of a subset of patients with occult HCV infection without the need to perform a liver biopsy.