BACKGROUND Neck dissection is commonly performed in the management of head and neck malignancy and may involve internal jugular vein (IJV) sacrifice. Potential complications include intracranial hypertension. This is well documented after bilateral neck dissection, although only scattered reports exist after unilateral IJV sacrifice. METHODS A 54-year-old man underwent unilateral left modified radical neck dissection for T1N2b squamous cell carcinoma of the tongue base. He presented 13 days postoperatively with symptoms of headache and diplopia. RESULTS Investigations revealed intracranial hypertension and bilateral abducens nerve palsies. He was treated with serial lumbar puncture, and his symptoms improved over the course of 2 weeks. CONCLUSIONS Intracranial hypertension sufficient to cause visual disturbance is a serious complication of unilateral neck dissection. Head and neck surgeons must be aware of this and have a low threshold for investigation of the signs and symptoms of intracranial hypertension in the postoperative period. © 2010 Wiley Periodicals, Inc. Head Neck, 2011.