Functional MRI holds great promise as a diagnostic tool in presurgical evaluation of patients with epilepsy. Recent research has used fMRI for localization of the seizure focus by tracking interictal spikes and by observing blood flow changes during seizure onset. Localization of the language-dominant hemisphere with fMRI has been well-validated in normal volunteers and left-hemisphere-dominant epilepsy patients, but is less developed for patients with mixed- or right-hemisphere language dominance. Intrahemispheric mapping of sensory and motor functions with fMRI is fairly well established, and progress is being made in mapping higher-level cognitive functions, particularly language. Little research has convincingly demonstrated hippocampal function in the normal brain during memory processing, and applications of memory mapping in epilepsy are still lacking. While the clinical use of fMRI in epilepsy needs substantially more study, this is nonetheless a very promising technique that may dramatically change the presurgical diagnostic regimen for these patients.