A total of 199 patients with abdominal aortic aneurysms were followed up to investigate the influence of selective management on the prognosis and the risk rupture of abdominal aortic aneurysms. Decisions to operate or to continue watchful waiting with treatment of risk factors for expansion were based on aneurysm size, expansion rate, aneurysm-related symptoms, and individual operative risk. Rupture occurred in eight cases. All aneurysms were larger than 5 cm, and six were larger than 6 cm in diameter at the last measurement before rupture. The resulting overall 5-year cumulative rate of rupture was 7.3% (Kaplan Meier). The 134 patients who underwent more than one ultrasound examination were observed for an average of 4.0 years (536 patient-years). The expansion rate was significantly correlated with the initial diameter and the diastolic blood pressure (best subset multiple regression analysis: r = 0.403; P < 0.001). A correlation with the systolic blood pressure was found only in univariate analysis (r = 0.236; P = 0.011). Amplitude of blood pressure, serum cholesterol level, low-density and high-density lipoproteins, ratio of low- to high-density lipoproteins age, and the extent of smoking habits were not correlated with the expansion rate. Our conclusion is that larger diameter and higher diastolic blood pressure are important risk factors for expansion of abdominal aortic aneurysms. Selective management of abdominal aortic aneurysms based on aneurysmal size, expansion rate, and patient characteristics may result in a low rate of rupture.