Graves' thyrotoxicosis with thymic hyperplasia and pericarditis has never been described in the literature. In this case report, we present the clinical, laboratory, and radiographic findings of a 24-year-old active duty male who was admitted for management of nonexertional, positional, pleuritic chest pain. Electrocardiography confirmed pericarditis as the presenting diagnosis. Laboratory findings revealed an undetectable serum thyrotropin level and further evaluation with a contrast chest computed tomography confirmed the presence of a goiter and an anterior mediastinal mass. The patient's pericarditis and thymic hyperplasia resolved with treatment of his Graves' disease.