Two cases of aortic dissection are presented in which discordance between renal perfusion and function has been demonstrated with Tc-99m DTPA. Renal perfusion on the affected side was decreased on blood flow imaging, whereas renal function, including parenchymal accumulation and excretion assessed by subsequent sequential imaging, were similar for both kidneys. These results suggest that blood flow imaging more readily demonstrates a unilateral renal abnormality in patients with aortic dissection.