A 34-year-old housewife with nonconvulsive status epilepticus was followed up for 20 years since the initial fit. She maintained some contact with reality during the stupor and recalled the episode to some extent, while the EEG showed continuous spike-wave complexes. During the clinical course, the main type of seizures was spike-wave stupor, of which the maximum frequency was several times a week in the hospital and the duration was many minutes to several hours, and also secondarily generalized convulsive seizures occurred approximately once a month. The lasting control of spike-wave stupor was not achieved in spite of the various medications for the long follow-up period. The ictal EEGs of spike-wave stupor always showed the frontal origin. The meaning of the term "nonconvulsive status epilepticus" in this case was briefly discussed.