Lemierre syndrome consists of septic thrombophlebitis of the internal jugular vein secondary to oropharyngeal infection, usually with Fusobacterium necrophorum. Septic metastatic emboli and distant infection are characteristic. We describe the imaging appearance of Lemierre syndrome in an adolescent female by both magnetic resonance imaging and computed tomography. This case illustrates the rapid onset and characteristic progression of the rare syndrome of Lemierre. In addition, we used magnetic resonance imaging to effectively distinguish between inflammatory venous thrombosis and abscess, thus avoiding surgery in our patient. Early directed antibiotic therapy is mandatory to ensure good outcome.