Background: The aim of the study was to evaluate the presenting symptoms and signs of idiopathic intracranial hypertension (IIH) in a large cohort of patients and to estimate their possible role in establishing the diagnosis of IIH. Methods: This prospective cohort study in two tertiary centers, the Danish Headache Center in Rigshospitalet-Glostrup and the Neurology Clinic of the Clinical Center of Serbia, included 286 patients referred by attending specialists for possible IIH evaluation. Patients were divided into two groups: one with confirmed IIH diagnosis and one with rejected IIH diagnosis. Results: The diagnosis of IIH was confirmed in 219 (76.6%) patients. It was more often confirmed if the patient was referred by an ophthalmologist than if the referral was from a neurologist (83.6% vs. 69.8%, p =.029) and in patients with higher body mass index (BMI) (p =.032). Transient visual obscurations (p =.006), double vision (p =.033), neck pain (p =.025), and tinnitus (p =.013) were presenting symptoms more frequently reported by patients with IIH diagnosis. In the same group of patients, papilledema (p <.001) and sixth nerve palsy (p =.010) were noted significantly more often. Papilledema was extracted by multivariate analysis as an independent predictor of IIH diagnosis (p <.001). Conclusion: Although studies investigating IIH report an abundance of presenting symptoms, our results indicate that these symptoms are not diagnostic for IIH. Papilledema is the most reliable clinical sign predicting the correct IIH diagnosis in patients with suspected IIH.