Neuroimaging techniques have had a dramatic impact on the evaluation and treatment of patients with epilepsy. In order to take full advantage of their potential, it is important to place them in clinical and electrophysiological context and to understand their technical limitations. Positron emission tomography with 18F-2-deoxyglucose and single photon emission computed tomography can provide valuable data for presurgical localization of epileptogenic zones. Interictal cerebral blood flow studies, however, using either positron emission tomography or simple photon emission computed tomography are unreliable. Positron emission tomography cerebral blood flow activation studies, on the other hand, are becoming very useful for presurgical cognitive mapping and may be able to replace the intracarotid amytal test for language and memory lateralization. There are a number of receptor ligands available for both positron emission tomography and simple photon emission computed tomography studies, including benzodiazepine, opiate, and cholinergic tracers. Increased mu opiate, decreased benzodiazepine, and increased monoamine oxidase B receptor binding have been reported.