The first report in the world literature of the condition which is now generally known as idiopathic retroperitoneal fibrosis was that of Albarran (1905), but the first report in the English language did not appear until that of Ormond (1948). Since then many further case reports have been published, but the aetiology of the condition remains obscure.The disease usually presents as a urological problem when the mass of retroperitoneal fibrous tissue causes deviation or obstruction of one or both ureters often resulting in hydronephrosis. It has become apparent, however, that the manifestations of the disease may not be limited to the pressure effects of the retroperitoneal lesion on neighbouring structures and that the disease may present as a systemic disturbance.Case Report A 64-year-old man awoke on January 1, 1965, with severe low back pain which persisted and was made worse by movement. For 3 days the pain was so severe that he was almost completely immobilized. There were occasional sharp shooting pains down the back of both legs and his back tended to "lock" after sitting. Following the onset of the pain he complained of general malaise, anorexia, and night sweats. There were no urinary symptoms. He was admitted to hospital on January 16.During the previous 20 years he had had several attacks of low back pain, each of which had been much less severe than this attack.Examination.-He was a stocky man. A mid-stream specimen of urine contained no albumen or sugar and was normal on microscopy and sterile on culture.Chest x ray showed a normal cardiac shadow and slightly increased markings at the right lung base.Intravenous pyelogram showed partial obstruction and some hydronephrosis of the left kidney; the right kidney appeared normal. These findings were confirmed by retrograde pyelography.Course.-The patient ran a continuous fever of 990 to 1020 F. By February 10 the haemoglobin had fallen to 10-4 g./100 ml.A laparotomy was performed on February 22, when the presence of a dilated left renal pelvis and retroperitoneal fibrosis was confirmed and a biopsy of the lesion taken. Post-operatively the patient was apyrexial. On the third post-operative day he developed atrial fibrillation with a ventricular rate of 120 per min., which was confirmed electrocardiograwhically. He was given digitalis. The following day he developed severe pain in the left praecordium which radiated down the left arm. The pain lasted for 4 hours and was associated with a soft apical systolic murmur and a few rales at both lung bases. A further electrocardiogram showed that the rhythm had reverted to sinus, but there were supraventricular and ventricular ectopic beats and ST depression, most marked in lead V4. The following moming the serum SGOT was 79 units.Termination.-Later that morning (February 27) the patient collapsed suddenly. The peripheral pulses were not palpable and the electrocardiogram showed ventricular fibrillation. Resuscitative measures which included direct current defibrillation resulted in only temporary restoration of...