THE PRESENT STUDY investigated the effects of diphenylhydantoin (Dilantin) as an agent for mitigating disruptive behavior in a sample of male juvenile delinquents. Neither a sedative nor a central nervous system depressant, diphenylhydantoin acts as an anticonvulsant by reducing the seizure process and limiting the development of maximal seizure activity. The drug serves to stabilize the threshold of nerve cells against hyperexcitability caused by excessive stimulation or environmental changes capable of reducing the membrane sodium gradient. Neuropharmacologically, this threshold-stabilizing action occurs through a decrease in the intracellular concentration of sodium in brain cells, in cardiac muscle, and perhaps universally in excitable membranes.1 Hypothetically, such active extrusion of sodium results from metabolic stimulation of the "sodium pump." A partial review of the literature on the use of diphenylhydantoin with nonepileptic populations strongly suggests that the drug may have some efficacy in curbing