Ultrasonography of the abdominal aorta was routinely performed in a consecutive series of 100 patients during postoperative reconvalescence after myocardial revascularization. The mean aortic diameter was greater in the male series (n = 80) then in the female population (n = 20) (2.17 +/- 0.85 cm vs 1.6 +/- 0.3 cm). Abnormalities were only seen in male patients over 50 years of age (n = 65). The overall incidence of aneurysm greater than or equal to 4 cm was 6%. The incidence of aortas at least 3 cm was 7/65 (11%). It is suggested that the incidence of unsuspected aortic aneurysm in this subgroup is high enough to justify continued screening programmes by ultrasound.