Status epilepticus refractory to initial anticonvulsant therapy is a serious condition with a high morbidity and mortality. We present 50 cases with refractory status epilepticus (RSE) treated with very-high-dose phenobarbital (VHDPB) without reference to a predetermined maximum level or dose. Maximum serum levels ranged from 70 to 344 micrograms/ml (median, 114 micrograms/ml). VHDPB controlled seizures in all cases where no limits were imposed upon maximum dose (47/50). We found no maximum dose beyond which further doses are likely to be ineffective. Forty patients were intubated prior to VHDPB, but recovered respiratory drive and could be removed from the ventilator despite very high serum levels. This is explained by acute drug tolerance. Hypotension was unusual, related to the highest levels, and easily controlled. VHDPB has many relative advantages over other therapies presently used for RSE.