Arteriovenous fistula of the renal vessels is an exceedingly rare abnormality. Review of the literature reveals only four such cases previously reported. Since the presence of a thrill or a bruit is a prominent clinical finding, it seems probable that the lesion can be suspected solely on the basis of the physical examination. We report here the fifth proved case and the first such case secondary to trauma. Case Report A 7-year-old girl was admitted to the Genesee Hospital for evaluation of hypertension. Approximately eighteen months prior to admission, she had fallen on a flight of stairs while carrying milk bottles. A report from the hospital at which she was treated at that time revealed that she was admitted in surgical shock. A puncture wound, 2 cm. in length, was found at the level of the eleventh rib in the left mid-axillary line. An exploratory operation was performed through a left supracostal incision, and a large retroperitoneal perforation of the descending colon, corresponding to the penetrating wound of the abdomen, was noted; blood and fecal material were spilled into the surrounding area. The kidney and perirenal structures appeared unaffected. The perforation was closed, and a drain was brought from the area through the wound. Additional treatment consisted of penicillin and streptomycin. Recovery was gradual but satisfactory. The patient's blood pressure was normal throughout hospitalization and was recorded as 108∕60 on the fifth day after injury. About fifteen months prior to her admission to the Genesee Hospital (three months after the injury), the child began to complain of frontal headache. At first, she averaged about three attacks a week, which were relieved by aspirin. During the past fifteen months, however, the headache had increased both in frequency and severity until at the time of the present admission it was almost constant. Recently her attending physician had noted a persistent hypertension. The past history was negative except for some enuresis, but this was evident before as well as after the accident. The patient did not appear in any distress on the admission physical examination. The temperature was 99°, the pulse 94, and respirations 20. The blood pressure was recorded as 146∕110. The heart was normal on percussion and auscultation. The eyegrounds were negative. The abdomen showed a well healed scar, 4 to 5 inches long, in the left epigastrium, extending toward the left flank, and a second scar of a half-inch incision in the left flank. Laboratory findings were as follows: hemoglobin 13.1 gm., red blood cell count 4,400,000, and white cell count 7,500; blood smear differential count and urine examination normal; blood non-protein nitrogen 27 mg. per cent. An electrocardiogram was interpreted as normal. On the second hospital day an intravenous pyelogram (Fig. 1) was made and interpreted as follows.