Despite adequate diagnostic evaluation and prolonged follow-up, the causes of epilepsy in the elderly patient frequently remain unknown. Some of these may be of occult, degenerative or vascular central nervous system disease origin--entities which are often difficult to incriminate specifically. Unquestionably, in a few cases, seizures occur at the time of the initial cerebrovascular accident, although in some patients seizures may follow such an episode after a latent interval, particularly when cortical motor areas have been damaged by the initial vascular insult. It is important to differentiate this group from those with recurrent vascular episodes, in whom diagnostic studies and treatment may differ. Brain tumour is as prominent a cause of seizures in the seventh decade as it is in younger adults, but probably is of lower incidence thereafter. Focal, clinical and electroencephalographic findings and a progressive clinical course are particularly common in this group. A heterogeneous group of causes, a few of which are liable to affect the ageing patient, are responsible for some of the seizures in old age and should be searched for when the etiology is obscure. Diagnostic studies will vary with the individual problem and, whenever possible, should be restricted to non-invasive studies such as electroencephalography and computer-assisted tomography, after initial baseline clinical assessment and laboratory studies have been performed. Contrast procedures such as angiography are sometimes hazardous to patients with atherosclerosis and should be reserved for selected patients. Treatment follows conventional guidelines with some modifications due to the vulnerability of the ageing patient to degenerative disease and complications of immobilization.