Pulmonary scintigraphy constitutes an important step in the non invasive diagnosis of pulmonary embolism (PE). This technique may be employed for the evaluation of the pulmonary perfusion alone, as in Italy and in the PISA-PED study, or else even for the evaluation of the pulmonary ventilation (as in Anglo-Saxon countries and in the PIOPED study). In the present study, the reasons which have prompted the ANMCO-SIC Commission for the Guidelines for The Prophylaxis, Diagnosis and Therapy of Pulmonary Thromboembolism to propose, for the diagnostic work-up of the patient with clinically suspected PE, the use of perfusion scintigraphy alone and of the classification criteria employed in the PISA-PED study instead of the more commonly utilized ventilatory-perfusion scintigraphy and of the criteria included in the PIOPED article, are discussed. Besides, the Commission's decision to consider PE as being present in case of agreement between the scintigraphic and clinical pictures, and to exclude this condition when the scintigraphic outcome is normal/almost normal regardless of the clinical probabilities, is also motivated.