A standardized questionnaire was administered to 100 patients suspected of having pulmonary embolism to investigate whether clinical data may be reliably used in the decision-making process of such patients. Questionnaire data were compared with lung scintigraphy outcome and 16 variables were selected as significantly associated with the scintigraphic diagnosis. Based on these variables, patients with abnormal scintigraphy compatible with pulmonary embolism and patients with scintigraphy not compatible with embolism were classified in accordance with the scintigraphic diagnosis. When these 16 variables were tested in an additional validation group, clinical and scintigraphic diagnosis matched in most cases. These results show that clinical data can be used to predict the outcome of lung perfusion scintigraphy in patients suspected of pulmonary embolism. Use of a standardized questionnaire can improve the accuracy of pretest assessment of such patients and positively influence the decisions to start heparin coverage or obtain pulmonary angiography.