Mononucleosis is a common disease of young adults manifested by lethargy, fever, pharyngitis, lymphadenopathy and splenomegaly. In this podcast, we review the clinical features of the disease and how good each of them is at establishing a diagnosis of mononucleosis. We also review how Epstein Barr virus was discovered as the cause of mononucleosis and talk to Mark H. Ebell, MD, MS, author of Does This Patient Have Infectious Mononucleosis? The Rational Clinical Examination Systematic Review. Articles discussed in this episode: Does This Patient Have Infectious Mononucleosis? The Rational Clinical Examination Systematic Review (2016) Acute Lymphatic Leukemia and Infectious Mononucleosis (1931) Infectious Mononucleosis: Part I. Clinical Aspects (1935)  Infectious Mononucleosis: Clinical Manifestations in Relation to EB Virus Antibodies (1968)