There are three well defined occlusive diseases of the arteries: thrombo-angiitis obliterans, thrombo-arteriosclerosis obliterans and occlusion due to embolism.1In our experience 95 per cent of the cases of occlusive disease of the arteries are accounted for by these three diseases. In the remaining 5 per cent are included a small number of unusual forms of obliterative arteritis, types which at present are of greater pathologic than clinical interest: aneurysm with thrombosis, cervical rib with thrombosis of the peripheral artery and an irregular form, present in a small number of cases, which for lack of a better term has been designated simple thrombosis.2It was recognized that the last-mentioned group of diseases probably represented a clinical entity, but until a sufficient number of cases were observed, the pathologic picture was studied and the course of the disease was followed over a period of years it would be impossible