Purpose: We evaluated the distribution of hypoperfusion in patients with traumatic brain injury (TBI) and the relationship of thalamic hypoperfusion to severity of cognitive and behavioral sequelae. Materials and Methods: Tc-99m ECD SPECT and MRI were performed in 103 patients (M/F=81/22, mean age 34.7±15.4 yrs) from 0.5 to 55 months (mean 10.3 months) after TBI. The patients were divided into three groups showing no abnormalities (G1), focal (G2) and diffuse injury (G3) on MRI. Psychometric tests assessed 11 cognitive or behavioral items. In all patients, we evaluated the distribution of hypoperfused areas in SPECT, and in 57/103 patients, neuropsychological (NP) abnormalities in patients with thalamic hypoperfusion were compared with those of patients without thalamic hypoperfusion. Results: The perfusion deficits were most frequently located in the frontal lobe (G1, 42.3%: G2 34.5%: G3 33.3%), temporal lobe (24∼26%) thalami (21∼22.4%), parietal and occipital lobe (≤10%). Numbers of NP abnormalities in the cases of cortical hypoperfusion with or without concomitant thalamic hypoperfusion were following: the former 4.7±1.5 and the latter 3.2±1.4 in G1, 5.0±1.1 and 4.8±1.2 in G2, 6.8±1.8 and 6.3±1.1 in G3, respectively. This difference according to thalamic hypoperfusion was significant in G1 (p=0.002), but was not significant in G2 or G3. Conclusion: SPECT in patients with TBI had demonstrated hypoperfusion mostly involving the frontal, temporal and thalami. In normal group on MRI, frontal hypoperfusion was more prominent than that of any other group, Furthermore in this group, SPECT could predict severity of NP outcome by concomitant thalamic hypoperfusion with cerebral cortical abnormalities.