We performed 99mTc-HMPAO SPECT in a patient during transient global amnesia and twice thereafter. SPECT during the attack showed a significant diminution of regional blood flow in the left thalamus and a less marked diminution in the right thalamus. Quantitative evaluation of global 99mTc-HMPAO uptake indicated a diffuse depression of cerebral blood flow. At follow-up to 40 days after the attack, global uptake and thalamic flow indices normalized, but there was a persistent reduction of left frontal flow values.