Monospot test is a simple proprietary test that detects the presence of heterophile antibodies which are typical of Epstein-Barr virus infection. The heterophile antibody is mostly IgM and usually rises during the second week of infection. EBV serology confirms the diagnosis however Monospot test is better used for screening. EB virus infects B cells and infectious mononucleosis caused by them presents with symptoms of fever, fatigue, pharyngitis, lymphadenopathy and splenomegaly. A negative heterophile antibody test should be repeated after the first week. If negative, then test for EBV- specific antibodies. Horse RBCs are usually used for agglutination reaction in monospot test.