Blood tests do not detect AIDS. Nowadays, the number of people suffering from AIDS is increasing and the danger is not small. AIDS is a human immunodeficiency disease, caused by HIV infection. The virus mainly attacks CD4-positive T cells. After the destruction of a large number of such cells, the immune system of the body is seriously damaged and is prone to a variety of infections and even malignant tumors after the low level, with a high death rate. In the laboratory by what method to detect, mainly HIV antibodies produced after the entry of HIV into the body. There are two methods of serological testing, the first is a preliminary screening test, called ELISA method, which is a major hospital to do the method, this method detects a positive, there is a suspicion of HIV infection. But the results need to be retested, and then retested or positive, we need to confirm the test. The confirmatory test is not done in the hospital, but at the CDC of the Center for Disease Control, where the immunoblot method is selected.