Background. The purpose of this study was to review arterial thromboembolic complications presenting with an acutely ischemic lower extremity after a kidney (KTx) or simultaneous kidney-pancreas transplantation (SPK) and to describe an approach to their management. Methods. We retrospectively reviewed all such transplantations (a total of 2109) performed between January 1985 and August 1995. We identified 16 recipients (incidence, 0.76%) in whom an acutely ischemic leg developed during the immediate postoperative period (within the first 48 hours). Results. Of the 16 recipients, eight underwent a KTx (incidence, 0.45%) and eight underwent an SPK transplantation (incidence, 2.90%). Median age was 38 years (range, 15 months to 61 years). Thirteen had insulin-dependent diabetes mellitus (IDDM), a significantly higher incidence than in the control group (i.e., transplant recipients without this complication) (p < 0.01). Peripheral vascular disease (PVD) was documented before operation in eight (50%) of the recipients (vs 8.9% in the control group) (p < 0.01). Ten were uremic (on chronic dialysis) before transplantation; six were nonuremic (not on dialysis). Intraoperatively, 14 had moderate to severe atherosclerotic disease affecting the iliac vessels, seven of whom required some manipulation of the artery (either endarterectomy or tacking of the intima) to make it suitable for anastomosis. Heparin was administered systemically during cross clamping to only four. Most of the 16 recipients showed symptoms or signs of arterial occlusion within the first few hours after operation. The most common symptom was pain; the most common physical finding was loss of femoral and distal pulses. Thirteen recipients had moderate to severe ischemia, as judged by physical examination; 15 returned to the operating room for surgical exploration. Eight underwent thrombectomy through an inguinal incision, with successful restoration of flow. Seven underwent exploration through the initial incision because of concern regarding the viability of the transplanted organ; five of them required transplant nephrectomy because of simultaneous thrombosis of the renal artery. No patient needed a bypass procedure to restore flow. Long-term morbidity as a result of the arterial occlusion was related to the severity and length of ischemia. Conclusions. On the basis of these results, we suggest the following recommendations: (1) all patients should undergo a thorough peripheral vascular examination before and after transplantation; (2) patients at higher risk for arterial thromboembolic complications (e.g., those with significantly diseased vessel at intraoperative examination, nonuremic patients) should receive intraoperative systemic heparin before cross clamping of the artery; and (3) patients with signs or symptoms suggesting arterial occlusion after operation should undergo prompt surgical exploration.