The aim of this study was to investigate whether intravenous heparin administration was associated with a reduction in perioperative mortality and late distal thrombectomy in patients with ruptured abdominal aortic aneurysms (AAAs). One hundred thirty-one patients had repair of ruptured AAA between January 1999 and January 2004. Sixty-three received heparin according to the consultant's preference at the time of the operation. Data were prospectively collected, and multivariate analysis was performed for independent predictive factors. Thirty-day mortality was 29%. Patients receiving heparin had lower perioperative mortality (16% vs 42%; p= .001). Heparin administration was not associated with increased hemorrhage or transfusion. Multivariate analysis confirmed that heparin administration was independently predictive of survival (p= .036). Other factors found to reduce survival were age (p= .023), smoking (p= .042), and systolic blood pressure (<100 mmHg) at presentation (p= .045). Fewer patients had thrombectomy after heparin (8% vs 12%), but this was not statistically significant. Perioperative complications were similar in both groups. The administration of systemic heparin before the clamp is applied to leaking aneurysms does not appear to increase hemorrhage and subsequent mortality and may reduce the need for early thrombectomy.