The etiology, clinical features and outcome of generalized major motor status epilepticus in 98 patients over the age of 14 years have been reviewed. Approximately half of the patients had not had previous seizures. The most common single cause of the status was noncompliance with anticonvulsant drug regimens and this accounted for the status in 53 percent of the patients with previous seizures and in 28 percent of all the patients in our series. The other causes in our series were alcohol-withdrawal, cerebrovascular disease, cerebral tumors or trauma (involving especially the frontal lobe), intracranial infection, metabolic disorders, drug overdose and cardiac arrest. In 15 percent of the patients, however, no specific cause could be found. Status was never the initial manifestation of primary (constitutional) generalized epilepsy in our experience. The etiology of the status was sometime multifactorial, so patients must be screened as fully as possible even when a likely cause is readily apparent. The motor manifestations of the convulsions were frequently restricted in distribution (62 percent of the cases). Focal or lateralized convulsive activity, especially during the course of continued seizure activity, did not necessarily indicate that localized structural pathology was responsible for the status. The seizures were of the tonic variety in a few of our patients and in such circumstances were usually associated with cerebral anoxia. We found that a poor outcome of the status was more likely as its duration increased, and the morbidity rate from the status itself was 12.5 percent among our patients, with a mortality rate of 2.5 percent. The episode of status was usually accompanied by hyperthermia, and often by a brisk peripheral leukocytosis, and in some of our patients a status-induced cerebrospinal fluid pleocytosis also developed. These features may lead to diagnostic confusion if their basis is not recognized. In most of our patients a systemic acidosis developed during the course of the status, but this did not appear to greatly influence the outcome.