HDV (Hepatitis D virus) causes the disease Hepatitis D. The virus is a small spherical enveloped virusoid. However, of all the five hepatitis viruses (A, B, C, D, E), HDV is said to be a sub viral satellite. It depends upon the presence of Hepatitis B virus. Liver diseases that are linked to Hepatitis B and D viruses are more severe than those patients infected with hepatitis B virus. This is one of the primary reasons why this test is necessary. Anti HDV antibody testing is done when a patient complains of abrupt onset of nausea, anorexia, jaundice, liver disease. About 20 million of the population is infected by HDV. The young generation comprising of the age group 20s and 30s are mostly infected with the virus. Presence of antibody Hepatitis D and HBsAg shows a co-infection. Such patients are susceptible to chronic hepatitis. Therefore anti HDV antibody testing is recommended for all patients with Hepatitis B infected virus. There can be acute HDV infection when there is a co-infection with HDV and HBV viruses, Superinfection due to chronic HBV carriers and HDV, and thirdly by hepatocytes by HDV.