Lidocaine (lignocaine) was given in 42 episodes of status epilepticus (SE) in 36 patients either because of limited pulmonary reserve (22 patients) or because of lack of response to diazepam (14 patients). Lidocaine (1.5-2 mg/kg) was given intravenously in two minutes. A further identical bolus was infused if no response had occurred or if seizures recurred. With the first bolus 11 episodes of SE did not stop, but 31 responded, always in less than one minute. In 19 episodes, however, this response lasted less than 30 minutes. Twelve episodes did not recur, but 30 needed a second bolus because of recurrence. Of these, 19 episodes responded at once but SE reappeared in seven. In these seven episodes the mean control time with the second dose was 102 minutes. Five of these subsequently responded to a continuous infusion of lidocaine. Eleven patients, who had not responded to the first bolus, had no response to the second. Lidocaine is a drug that may be epileptogenic at high doses. At the doses used here, however, lidocaine seems to be a rapid acting anticonvulsant, useful in the short term management of SE and may be indicated in patients in whom respiratory or consciousness depression is undesirable and in those with no response to diazepam. The absence of response to lidocaine indicates SE resistant to treatment and poor prognosis. These data show that prompt lidocaine administration may be worthwhile when management of respiratory depression is not possible.