Twenty-one patients who developed one or more episodes of postictal hyperactive delirium (PHD) during the course of electroconvulsive therapy were given a new benzodiazepine drug, midazolam (MDZ), for sedation in an open, uncontrolled clinical trial. MDZ was found to be safe in all patients and was effective as treatment or prophylaxis for PHD in at least 20 patients. Rapid onset of action, brief duration of clinical effects, rapid biotransformation and elimination, wide choice of administration route, and a favorable toxicity profile make MDZ an attractive agent in the management of PHD. The relevant clinical pharmacology of MDZ is reviewed and additional observations regarding PHD are discussed.