A total of 61 patients with myelodysplasia underwent water cystometry and electromyography of the external sphincter. Of these patients 27 underwent video fluorourodynamics as a part of preoperative evaluation or instead of a voiding cystometrogram. Renal quantitative scintillation camera studies detected 7 patients with mild upper tract deterioration, even when other tests failed to do so. A total of 31 patients had upper tract deterioration as detected by excretory urography, ultrasound and/or renal scan studies, and were designated as group 1, while 30 had normal upper tracts and were designated as group 2. Bladder compliance in group 1 was significantly lower than that in group 2 (4.5 versus 11.3 ml./cm. water, p = 0.001). Leak pressure in group 1 was significantly higher than in group 2 (42.3 versus 26.1 cm. water, p = 0.019). In summary, patients with evidence of upper tract deterioration had lower bladder compliance and higher leak pressure than patients with normal kidneys.