Five cases involving the treatment of longstanding, severe, and previously unmanageable self-injurious behavior are presented. In each case, the behavior was forceful contact with the head or face, and treatment consisted of mild and brief contingent electrical stimulation, delivered automatically or by a therapist, via the Self-Injurious Behavior Inhibiting System. Results of reversal and/or multiple baseline designs, in which sessions ranged in duration from 10 min to all day across a variety of settings, showed that the effects of the system were immediate and produced almost complete elimination of the self-injurious behavior. Controlled and anecdotal follow-up data for four of the five cases suggest continuing benefits and the absence of detrimental side effects associated with treatment. Potential applications of the device, as well as extensions and limitations, are discussed.