The utility and safety of sequential B-mode ultrasonography to treat male patients with small (less than 6.0 cm in diameter) abdominal aortic aneurysms (AAAs) were studied retrospectively in 149 consecutive patients. Sixty-three of these patients have had operative repair of the AAA. Eight-six remain unoperated on. Mean growth rate was 0.79 cm/y (1.06 cm/y in the operated-on group and 0.36 cm/y in the unoperated-on group). Seven patients sustained rupture of the AAA during follow-up and 4 patients died as a consequence of elective repair, for a combined mortality rate of 7.4% (11/149). Only one AAA that was less than 5.0 cm ruptured. This has proved to be an effective way to manage AAAs in this population.