An analysis of dynamic CT curves in 12 patients with acute renal failure was performed. An oliguric patient who demonstrates corticomedullary differentiation on CT images will develop diuresis within 4 days. A corticoaortic junction time of more than 180 s associated with no differentiation between cortex and medulla is associated with prolonged oligoanuria. Impending diuresis is heralded by a corticoaortic junction time of less than 180 s. These preliminary results suggest that an analysis of dynamic CT curves in acute renal failure can predict the time of appearance of the diuretic stage.