Spinal cord injury patients are at increased risk for urolithiasis and many will require treatment, most commonly with extracorporeal shock wave lithotripsy. New, second generation lithotripsy devices allow treatment without tub immersion, and without general or regional anesthesia for most patients. Spinal cord injury patients, with loss of sensation below the level of injury, would seem to be ideal candidates for such treatment. We present our experience with 20 consecutive spinal cord injury patients treated without anesthesia on the Medstone STS second generation lithotriptor. All patients were awake and experienced no direct sensation from the shock waves. All but 1 patient (T12 level), however, experienced autonomic dysreflexia, with significant elevations in systolic blood pressure (mean increase 44 mm. Hg, maximum 74) and diastolic blood pressure (mean increase 24 mm. Hg, maximum 61), with reflex bradycardia (mean decrease -22 beats per minute). Autonomic dysreflexia was successfully treated in this setting with short-acting sublingual nifedipine. Associated bradycardia was treated with atropine in 6 patients. Preoperative bowel preparation proved to be useful in spinal cord injury patients to maximize stone imaging and may decrease autonomic dysreflexia if this is caused by shock waves impacting on the distended bowel. Other problems included uncontrolled skeletal muscle spasms elicited by shock waves, which proved to be troublesome in maintaining patient position and stone localization. Muscle spasms were decreased with benzodiazepines. Care was also observed in spinal cord injury patients to pad all pressure points on the hard, dry treatment surfaces associated with second generation lithotriptors and, thus, prevent skin breakdown.