The hypothesis that the type of first assistant who attends the surgeon influences the course and outcome of graft replacement for abdominal aortic aneurysm was tested. Surgical results were analyzed in 179 consecutive patients (149 men and 30 women; mean age, 69 +/- 7.5 years). All the operations were performed by the author-an experienced surgeon with a practice limited to general vascular surgery. The choice of first assistant was based solely on availability; 110 (61%) patients had a board-certified surgeon as the first assistant and 69 (39%) had an experienced registered nurse as the first assistant. Patients with intact aneurysms undergoing elective surgery were in Group 1, and patients with intact aneurysms undergoing urgent surgery were in Group 2. Group 3 patients included those who had ruptured aneurysms but were hemodynamically stable, and Group 4 patients had ruptured aneurysms and were in shock. The distribution of patients was similar in each first-assistant group, as was the use of straight and bifurcated graft reconstructions, associated visceral procedures, and other adjunctive procedures. The hospital mortality was 4% (6/149) for Group 1 patients, 12% (2/17) for Group 2,20% (1/5) for Group 3, and 50% (4/8) for Group 4 patients. The morbidity and mortality rates were independent of the type of assistant, as were the operative time, blood loss, and adjusted blood transfusion volume. These results suggest that the choice of either an MD-surgeon or an experienced RN as first assistant does not influence the course or outcome of abdominal aortic aneurysm surgery.