In patients in whom there is clinical suspicion of pulmonary thromboembolic disease, because of the risk of inadequate treatment, definitive radiologic evaluation should be carried out. Of the diagnostic procedures available, conventional pulmonary angiography has the greatest sensitivity and specificity in the detection of pulmonary embolism or other pulmonary vascular disease. Pulmonary angiography is indicated for patients with an indeterminate lung scan, for those with a high-probability lung scan in whom confirmation is necessary because of high risk for bleeding complications from anticoagulation, if embolism is massive and embolectomy is contemplated, if thrombolytic therapy or vena cava interruption is considered or if there is significant clinical evidence for an alternative diagnosis as well as for those with low-probability scans with a high degree of clinical suspicion and to complete a workup in patients with pulmonary hypertension. Refinements in the technique have simplified and expanded its application. The hemodynamic evaluation with right-heart catheterization before and after pulmonary angiography plays an important role in the choice of treatment of pulmonary embolism. In patients with multiple bilateral lobar or segmental perfusion defects, performance of right and left pulmonary arteriography in the right and left posterior oblique projections should be carried out. In the presence of additional pulmonary hypertension, the lung in which perfusion is most abnormal is selected first for angiography with a low bolus contrast dose. The angiographic criteria for the diagnosis of pulmonary embolism are intraluminal vascular filling defects or an abrupt cutoff of a large vessel. For selective opacification of lobar pulmonary branches occlusion pulmonary angiography is helpful. The mortality of pulmonary angiography in experienced centers is approximately 0.3%. Complications may include cardiac perforation in up to 1% and subendocardial injury in less than 0.2%. In patients with pulmonary embolism but no pulmonary hypertension, treatment with heparin for ten to 14 days should be followed by coumadin anticoagulation for at least three to six months. For obstruction of greater than or equal to 50% of the pulmonary vascular cross-sectional area and pulmonary hypertension thrombolytic therapy should be given and insertion of an inferior caval filter can be considered. In those with more than 75% pulmonary vascular obstruction and corresponding hemodynamic derangement, pulmonary artery embolectomy or thrombolytic therapy should be carried out.4