The high mortality rate of pulmonary embolism requires rapid and rational diagnosis especially with regard to the necessary decision about the best possible treatment. Analysis of data published in the literature, and of our own data, show that angiography of the a. pulmonalis according to the i.v. DSA technique is of central importance. This involves fewer hazards than conventional pulmonalis angiography while being comparatively satisfactory in respect of reliability of the results (more than 90%). It is, therefore, a safe basis for deciding on the appropriate treatment: lysis or surgery.