The syndrome of increased intracranial pressure without hydrocephalus or mass lesion and with normal CSF composition, previously referred to as pseudotumor cerebri, is a diagnosis of exclusion now termed idiopathic intracranial hypertension (IIH). Diagnostic criteria of this disorder have not been updated since the Modified Dandy Criteria were articulated in 1985. Since then, new developments, including advances in neuroimaging technology and recognition of additional secondary causes of intracranial hypertension, have further enhanced the ability to diagnose conditions that may mimic IIH. These factors are not addressed in the Modified Dandy Criteria. This report describes updated diagnostic criteria for IIH that may be used for routine patient management and for research purposes.