The effect of ascorbic acid on urine pH was studied in spinal cord injury patients. Their urine was not colonized by urease positive microorganisms. The study was designed to compare the baseline urine pH value and the urine pH value after the administration of placebo or ascorbic acid 500 mg/6 h. The diet and medical treatment were not controlled. A significant decrease in urine pH value was not obtained. There was no clinical benefit from the use of ascorbic acid.