Epsten-Barr virus oropharyngeal shedding has been demonstrated in infectious mononucleosis patients many months after acute illness and long after the disease hallmarks, atypical lymphocytes and heterophile antibody, have disappeared. Extracellular virus is present more frequently in saliva than in other oropharyngeal samples. Prolonged excretion of EBV in asymptomatic carriers explains the difficulty in tracing case-to-case spread and increased transmissibility in age groups in which salivary exchange is high.