Neurologic and respiratory decompression sickness (DCS) symptoms occurring in the same individual represent complications rarely observed in altitude research. A case is presented of multi-symptom serious DCS resulting from exposure to 12,192 m (40,000 ft). Following 90 min of preoxygenation, the patient was decompressed in a hypobaric chamber from ground level to 12,192 m in 30 s. After 69 min at altitude he developed substernal chest pressure and the flight was immediately terminated. During the chamber descent the patient appeared disoriented. By 5486 m (18,000 ft) his chest pressure had resolved. The post-flight medical exam revealed multiple neurological abnormalities. He underwent a Table VI hyperbaric oxygen treatment with complete resolution of all abnormal neurological findings.