How long does it take to get the results of a blood test in a hospital is closely related to the items that are drawn and tested. 1. Checking the blood type generally takes about 20 minutes to get the results, so you can know whether the patient has type A, type B, or type O or AB blood. If you are looking for routine blood tests, you can usually get the results within an hour, and you will know the number of white blood cells, red blood cells, platelets and the ratio. 2, The time required for serological tests, such as hepatitis B antibody, hepatitis B five, hepatitis C antibody, syphilis antibody, AIDS antibody, tumor markers and rheumatoid factor, etc., is much longer, generally taking about 5-6 hours. Therefore, there are various items that can be tested in the hospital for blood tests, and the time required for the tests is closely related to the items tested.