ICU physicians generally rely on either narcotics or benzodiazepines to provide analgesia and sedation. We describe five patients in whom ketamine administered as a bolus dose of 0.5 to 1.0 mg/kg, followed by a continuous infusion of 10 to 15 micrograms/kg.min, provided effective sedation and analgesia without significantly compromising cardiorespiratory function. Four of these patients previously experienced deleterious cardiorespiratory effects from either benzodiazepines or narcotics. In three patients who were breathing spontaneously, PaCO2 remained less than 44 torr during the ketamine infusion. With ketamine, no reduction in mean arterial pressure from baseline was noted in any patient. As with any form of iv anesthesia, ketamine can have cardiorespiratory side-effects; therefore, the means to manage these effects should be readily available.