Smoking is an important risk factor for abdominal aortic aneurysm. Limiting the growth rate of small aneurysms has the potential to prevent them reaching a size at which surgical repair is considered. In 43 patients, with small aneurysms, growth rates were studied by serial ultrasound over 3 years. The median expansion rate of these small aneurysms was 0.13 cm per year. Growth rates were higher in those who continued to smoke (0.16 vs 0.09 cm per year in those who no longer smoked, p = 0.038). Higher growth rates were significantly correlated with the concentration of serum cotinine. Stopping smoking could reduce the growth rate of small abdominal aortic aneurysms.