26 patients subject to clinical convulsive phenomena, and 15 patients without clinical histories of seizures were successively recorded electroencephalographi-cally during sleep, during insulin-induced hypoglycemia and during the admn. of subconvulsive doses of Metrazol. This work was undertaken to evaluate the relative effectiveness of each of these most generally used provocative procedures on each individual patient. Sleep was the least effective agent in the elicitation of abnormal electric activity. Metrazol generated an equal ratio of spike-dome discharges in the epileptic patients (13 out of 26) and in the controls (7 out of 15). Insulin-induced hypoglycemia was intermediate between sleep and Metrazol as an effective provocative procedure. The "control" series was heavily weighted by narcoleptic patients and by individuals exhibiting aggressive behavior. In a larger series of "unselected control" patients the ratio of positive reactors was 1 in 10. Consequently it appeared that Metrazol was a most effective generator of spike-dome activity, and that it correlated well with evidence of clinical seizures. Also, it appeared self-evident that the elicitation of spike-dome discharges was not synonymous with clinical epilepsy, in that some of the control patients showed entirely similar electric activity.