A considerable proportion of patients with thrombosis of the aorta or its bifurcations exhibit low back pain either alone or in conjunction with other symptoms of this disease. Arterial obstruction should be considered in every patient presenting himself with low back pain. The importance of the history in making this diagnosis cannot be overemphasised. Back or leg pain, or both, coming on after exertion should suggest the diagnosis even in the absence of the other well recognised symptoms of arterial insufficiency. Therefore, to affirm or deny this suspicion, it is essential that palpation of the femoral and peripheral pulses be made a routine and integral part of every orthopaedic examination in patients complaining of low back pain. When pulses are not palpable or are diminished, and in the absence of other clear musculo-skeletal disease, consideration should be given to further and more specific diagnostic procedures, such as aortography. Only in this way can an occasional baffling and elusive case of troublesome backache be fully understood and the appropriate treatment instituted.