A comparative study was carried out on a radio-immunoassay (RIA) and enzyme-immunoassay (EIA) method for detecting the hepatitis markers anti-HBs, anti-HBc and HBsAg. The results indicated that the RIA and EIA were comparable for the HBsAg marker but that the RIA test was more sensitive for anti-HBs and more specific for anti-HBc. The conclusion was that if the EIA test is used for these markers, the laboratory and clinician must be aware of these limitations.