Thirty-one cases of infectious mononucleosis treated with Interfon-Alpha were reported. The dose of intramuscular injection was one million units per day for 5-7 days. The recovery course of fever, angina, lymphadenopathy and hepatosplenomegaly was much shorter in the study group than in the control group (27 cases). The results suggested that interfon-Alpha should be efficacious against EBV activity and might shorten the course of this disease.