Two patients who were suspected of having arteriovenous malformation(AVM) by plain and contrast enhancement cranial CT were examined by brain SPECT with I-123-IMP. One case, which showed defects on early and delayed images, was diagnosed as AVM. The other was diagnosed as cerebral infarction with luxury perfusion, based on the finding of hyperperfusion on two images. The final diagnoses of these two patients were confirmed by angiography and/or operation. We considered brain SPECT with I-123-IMP to be very useful for the differentiation between AVM and cerebral infarction with luxury perfusion, which was suspected of being AVM by cranial contrast enhancement CT.