Hepatitis B surface antigen (HBsAg) is the first serologic marker appearing in the serum at 6 to 16 weeks following exposure to HBV. In acute infection, HBsAg usually disappears in 1 to 2 months after the onset of symptoms. Persistence of HBsAg for more than 6 months in duration indicates development of either a chronic carrier state or chronic HBV infection. HBsAg HEPA CARD is used for detection of surface antigen of the hepatitis B virus. It can detect all the eleven sub-types of HBsAG It has a sensitivity of 100% and Specificity:99.4% according to WHO Evaluation.