Lemierre's syndrome, a rare and almost forgotten cause of internal jugular vein thrombosis, is usually caused by an anaerobic head and neck infection. Left untreated, it can result in the release of septic emboli. We describe the case of a 42-year-old man who presented with fever and a tender, swollen neck mass. Computed tomography revealed an edematous parapharyngeal area and a compressed internal jugular vein. Despite antibiotic treatment, the patient's condition worsened, and a parapharyngeal fluid collection was drained 4 days later. Six weeks later, the patient returned to the outpatient department complaining of headaches, and he was found to have a tender, firm neck. He was readmitted, and magnetic resonance venography revealed a right internal jugular vein thrombosis that extended intracranially to the sigmoid sinus. He was anticoagulated for 6 months, and he remained well during outpatient follow-up. We examine the controversial roles that anticoagulation and thrombolysis play in Lemierre's syndrome and sigmoid sinus thrombosis, and we review the diagnostic options.