Idiopathic intracranial hypertension (IIH), also known as pseudotumour cerebri,has an estimated incidence of 1 to 2 in 100,000 people per year. IIH commonly affects obese young women, where its pathogenesis, however, is not clearly understood. Patients present to the emergency department with a wide array of presentations. In light of this, we present a case of isolated sixth cranial nerve palsy in a non-obese young woman due to IIH in which brain imaging studies showed no abnormality;however,lumbar puncture reveals an opening pressure of more than 50 cmH2O. This case would help to alert physicians to consider IIH as one of the differential diagnoses when encountering such cases, as an uncommon presentation in the non-obese patient, and prompt referral is important to avoid unnecessary delay in the treatment of IIH.