Purpose: To investigate the perfusion of pulmonary nodules and the flow pattern revealed by electron beam tomography (EBT), and to evaluate their usefulness in the differential diagnosis of pulmonary nodules. Materials and Methods: A prospective perfusion study involving 28 nodules in 23 men and five women (meanage, 57 years) was performed using EBT with the multislice flow mode. There were four phases. Precontrast density (Hounsfield units, HU) in phase 0; perfusion, peak HU and time to peak in phase 1; and mean HU and percentage decrease of HU to peak HU of phase 1 in phases 2 and 3 were measured and compared according Results: Malignancy was diagnased in 19 cases [primary lung cancer (n=14); metastatic nodules (n=5)], while nine nodules were benign. Perfusion was significantly higher in malignant nodules than in benign (P<0.001) and a higher mean delay 1 HU (P<0.05) and a significantly short time to peak (P<0.05) were recorded in malignant nodules. In primary lung cancer cases, perfusion was significantly high compared with benign nodules(P<0.001), and a mean delay 1 HU was observed (P<0.05). There was no significant difference in perfusion Conclusion: Perfusion and flow pattern data measured by EBT can provide the useful information for differentiation between malignant and benign pulmonary nodules.