The diagnosis of hepatitis C is based on the detection of total anti-HCV antibodies using third-generation ELISA tests, and the detection and quantification of HCV RNA using real-time PCR with a detection limit of 10–15 IU/mL. These tests are typically performed on serum or plasma obtained from a venous blood sample that has been centrifuged by a clinical laboratory. Alternatives to ELISA techniques on serum or plasma are now being developed, such as immunological tests on cards or strips that detect anti-HCV antibodies (rapid diagnostic screening tests) and non-immunological tests on filter paper that detect and potentially quantify HCV RNA. These tests use biological matrices such as subcutaneous fluid or whole capillary blood collected from a fingerstick. These methods enable patient-side testing, or "point-of-care testing" (POCT). The development of reliable tests, along with the demand from health authorities to promote mass screening in industrialized countries and diagnosis in developing countries, should enable these tests to play a prominent role in clinical practice. Prospective evaluations of rapid diagnostic tests (RDTs) are now needed to establish their analytical performance and indications, and to understand their advantages and limitations in screening strategies. Standardization, particularly through the automation of blotter paper analysis, is essential if this type of medium is to be used on a larger scale. (R.A.)