The diagnosis of mislaying forms of pulmonary embolism, where even angiography was not pathognomonic, induced the use of a phlebography on lower limbs in patients where this diagnosis was suspected. The revelation of a distal thrombo-phlebitis and even more so an iliocaval one, becomes a major value when the clinical and paraclinical data remained arguable. The comparative study of diagnostic usual clinical and paraclinical elements (radiographies, E.C.G., gasometries and scintigraphies) confirmed, in 22 patients, the value of phlebography. On a pneumological background, it is useful to perform this examination, most of the time : a) on patients over 55, when a cardiorespiratory decompensation remained unexplained in a patient with chronic respiratory insufficiency, or even an unproved hemoptysis; b) but mostly before 55, in case of painful pneumopathy above all if it is bilateral and recurring, or in case of paroxysmal bronchospasm without atopic ground, when a belated asthma could be thought of. Finally vascular tests induced the fitting in situ of a clamp or "umbrella" in the vena cava in 7 patients out of 22.