To investigate the effect of current bladder management techniques on renal function in spinal cord injury (SCI), we followed 99 patients by frequent examinations, excretory urograms, and iothalamate short renal clearances. Fifty-eight percent of the subjects emptied their bladders by catheter-free methods (bladder retrained), 32% by intermittent self-catheterization, and 10% by indwelling urethral catheters. All remained clinically well, but more and earlier excretory urogram abnormalities occurred in the intermittent self-catheterization group. Twenty-one percent of the intermittent self-catheterization group but only 5% of the bladder retrained group had excretory urogram abnormalities. Declines of more than 10% in short renal clearance values were noted in 30% of intermittent self-catheterization patients and in 15% of bladder retrained patients. Our preliminary data support the need for close surveillance and follow-up after SCI rehabilitation, even in patients appearing clinically well. These data also suggest that renal function can be preserved with current bladder management methods, with bladder retraining having a slight edge over intermittent self-catheterization.