We analyzed the medical records of patients with an established diagnosis of acute renal infarction to identify predictive parameters of this rare disease. Seventeen patients (8 male) who were admitted to our emergency department between May 1994 and January 1998 were diagnosed by contrast-enhanced computed tomography (CT) as having acute renal infarction (0.007% of all patients). We screened the records of the 17 patients for a history with increased risk for thromboembolism, clinical symptoms, and urine and blood laboratory results known to be associated with acute renal infarction. A history with increased risk for thromboembolism with 1 or more risk factors was found in 14 of 17 patients (82%); risk factors were atrial fibrillation (n = 11), previous embolism (n = 6), mitral stenosis (n = 6), hypertension (n = 9), and ischemic cardiac disease (n = 7). All patients reported persisting pain predominantly from the flank (n = 11), abdomen (n = 4), and lower back (n = 2). On admission, elevated serum lactate dehydrogenase was found in 16 (94%) patients, and hematuria was found in 12 (71%) of 17 patients. After 24 hours all patients showed an elevated serum lactate dehydrogenase, and 14 (82%) had a positive test for hematuria. Our findings suggest that in all patients presenting with the triad--high risk of a thromboembolic event, persisting flank/abdominal/lower back pain, elevated serum levels of lactate dehydrogenase and/or hematuria within 24 hours after pain onset--contrast-enhanced CT should be performed as soon as possible to rule out or to prove acute renal infarction.