BACKGROUND Lemierre's syndrome (LS), a potentially fatal condition, is characterized by thrombophlebitis of a head or neck vein secondary to a head or neck infection, most commonly involving Fusobacterium necrophorum. Its association with polycythemia vera (PV) is not well reported despite the predisposition to thrombogenesis. CASE REPORT We present the case of a 66-year-old woman with a known history of polycythemia vera (PV) who presented with 4 days of worsening right-sided neck pain and odynophagia. The physical examination revealed poor oral dentition, mild erythema of the posterior pharyngeal mucosa, and non-erythematous tonsils without exudate. A computed tomography with i.v. contrast of the neck revealed complete thrombosis of the right internal jugular vein (IJV). Treatment was initiated with i.v. antibiotics and anticoagulation, with symptoms improving rapidly within 24 h. She was eventually discharged on apixaban and clindamycin and was encouraged to follow up with her hematologist. CONCLUSIONS PV predisposes patients to a hyper-viscous and prothrombotic state, which may warrant a stronger suspicion of Lemierre's syndrome. In addition, lack of aspirin use for prophylaxis of thrombosis and undiagnosed oral infection are factors to consider when assessing risk factors for Lemierre's syndrome in PV patients.