Acute infectious mononucleosis, caused by Epstein-Barr virus (EBV), is a self limited lymphoproliferative illness that is common in adolescents and young adults. It shows many complications in multiple organ systems, but the hepatobiliary and the respiratory complication is uncommon. We report a case with thickened gallbladder wall and pneumonia as complications of acute infectious mononucleosis in a child. Also the related literature were reviewed. A 4 year old boy presented with a history of high fever, cough, and abdominal distension for 20days. Physical Examination revealed audible crackles in whole lung field and gross hepatomegaly. Chest X-ray showed pneumonia and liver function tests were abnormal. Ultrasonography and computed tomography revealed a thickened gallbladder wall and hepatosplenomegaly. The diagnosis of primary Epstein-Barr viral infection was eventually made by specific serologic tests. The patients’s fever subsided 6 weeks later and pneumonia was recovered around this time. Liver function tests returned near normal 2 months later and ultrasonography of gallbladder was normal at this time.