The purpose of this study was to determine the usefulness of 99mTc-HMPAO-labeled leukocyte scans in the diagnosis of prosthetic vascular graft infection. METHODS We performed 75 scans in 61 patients with vascular grafts. Thirty-six patients were evaluated for suspected infection and 25 were control patients. Scintigraphic images were performed at 5 min, 30 min, 3 hr and, occasionally, 24 hr. Persistent increased uptake at 3 hr along the suspected area of the graft was considered evidence of graft infection. RESULTS All 20 infected grafts were detected with 99mTc-HMPAO leukocyte scan. The sensitivity and specificity of the scan in the detection of infected graft were 100%. We also detected two pelvic abscesses, two infected fistulae, two soft-tissue infections, three cases of ischemic colitis, one acute diverticulitis, one infected hematoma, one septic arthritis and one noninfected hematoma. One patient with a superficial groin infection had a negative scan. The eight pseudoaneurysms did not show scintigraphic evidence of graft infection. Correlative CT studies were performed in 12 cases. CONCLUSIONS Technetium-99m-HMPAO-labeled leukocyte scan is an accurate and valuable diagnostic method for evaluation of suspected prosthetic vascular graft infection.