The objective of this study was to elucidate the relationship between outcomes from carotid endarterectomy (CEA) in patients with and without renal insufficiency. Carotid endarterectomy is one of the most commonly performed vascular procedures. The role of cardiac comorbidity in carotid endarterectomy has been extensively studied. The relationship between renal failure and surgical outcomes has also been studied for both coronary artery bypass grafting and lower extremity occlusive disease. However, the role of renal insufficiency in relationship to decision making regarding surgical intervention for carotid stenosis is not well defined. The authors hypothesized that the outcomes from CEA were negatively influenced by renal dysfunction. A retrospective review was made of consecutive CEAs performed at their institution from 1990 to 1995. Patients were grouped into 2 categories according to their renal function. Group A, 448 patients (90%) with creatinine level 1.8 mg/dL or less, and group B, 49 patients (10%) with creatinine levels more than 1.8 mg/dL. Data from patients on dialysis are presented but were excluded for the purpose of analysis. Included in the study were 497 patients with a mean age of 70 +/-8.9 and 74 +/-8.9 for groups A and B, respectively. Preoperative creatinine was 1.1 (+/-0.25) mg/dL for group A and 2.5 (+/-0.81) mg/dL for group B. Outcomes were as follows: perioperative cardiac events 5.4% vs 28.6%, stroke rates 2.7% vs 2.0%, and mortality rates 0.9% vs 8.2%, for groups A and B, respectively. At 60-month follow-up the stroke rates were 7.6% vs 6.1 %, and the mortality rates 22.8% vs 59.2%, for groups A and B, respectively. While patients with chronic renal insufficiency have no increased risk of perioperative or long-term neurologic events, perioperative and long-term mortality rates are significantly increased. This significant reduction in survival should prompt a more cautious application of CEA in patients with increased creatinine.