The role of perfusion lung scintigraphy in the diagnosis of pulmonary embolism (PE) is reviewed. During the study 227 perfusion lung scans were obtained. The scans were grouped according to the PIOPED criteria into 5 groups: normal scans, very low, low, intermediate and high PE probability. The perfusion scans were analyzed according to the original PIOPED criteria, without ventilation scans. Evidence is provided that a normal perfusion scan excludes pulmonary embolism, and that a high probability lung scan, defined as a segmental perfusion defect with locally normal chest X-ray or findings in X-ray are smaller, sufficiently confirms the presence of pulmonary embolism in the majority of these patients (92.2%).