Neurostimulators used to treat chronic, intractable pain have evolved from technical developments in pacemaker technology. A totally implantable spinal cord stimulation (SCS) system was designed based on elements of a widely used cardiac pacemaker. This paper reports on the transformation of pacemaker technology for neurostimulation applications and presents results of using this system for the treatment of 90 patients with chronic, intractable pain of the low back and/or legs. Significant reduction in pain levels resulted from use of a totally implantable spinal cord stimulation system. Seventy percent of the patients experienced good or excellent pain relief at an average of 14.5 months after implant. Patients who used an automatic ON/OFF cycling mode of stimulation reported greater pain relief than patients who were stimulated continuously.