United States guidelines endorse one-time HCV antibody screening at HIV diagnosis. Rescreening HCV-seronegative patients on a regular basis is still not policy, although HIV-infected persons have reasonably substantial HCV incidence. We evaluated routine risk factor-independent HCV antibody re-testing in a Rhode Island HIV clinic. We instituted annual HCV antibody testing for HCV-seronegative patients who had not been rescreened in a year or more. Testing based on clinical suspicion continued. We conducted a chart review of new antibody-positive cases in the first year of rescreening, July 2006 to June 2007. Of 245 rescreened patients, 11 (4.5%) seroconverted. Five (45%) were female. Median time between last negative and first positive result was 32 months (range 8-98 months). Six (55%) had documented risk factors and 6 (55%) elevated ALT (> 45 IU/L) between antibody tests; none prompted re-testing. One seroconverter died of hepatocellular carcinoma 3.7 years after HCV diagnosis. A twelfth was rescreened for suspected acute HCV based on ALT of 515 IU/L. He had newly detectable HCV RNA then seroconversion, and achieved SVR following 6 months of treatment in the acute phase for genotype 1 infection. Incident HCV is not uncommon among HIV-infected patients in care. Rescreening identified undiagnosed HCV in this population. HCV RNA should be checked promptly in HCV-seronegative persons with ALT elevation. We observed consequences of late diagnosis (hepatocellular carcinoma) and benefits of early diagnosis (cure with treatment of acute HCV). Adding annual rescreening to the Ryan White Program would facilitate earlier identification of undiagnosed HCV and create an instant widespread surveillance system, providing HCV incidence data.