In view of the growing incidence of degenerative origin among the aetiologies of aortic regurgitation, we felt it interesting to report our experience of the surgical treatment of such patients. Out of 313 patients operated on for isolated chronic aortic regurgitation between 1974 and 1989, 102 (32.6%) had aortic regurgitation of degenerative origin and form the basis of this study. The patients were divided into group I (n = 48) without aneurysm of the ascending aorta and group II (54 patients) with anulo-aortic ectasia. The first group was further subdivided according to the diameter of the ascending aorta: in group Ia (23 patients) the aorta was normal with a root diameter of less than 40 mm, while in group Ib (25 patients) the aorta was enlarged (root diameter between 40 and 54 mm). There was no statistically significant difference between the pre-operative and operative parameters of patients in groups Ia and Ib. All underwent aortic valve replacement without associated surgery of the ascending aorta. During a mean follow-up of 58 months, five patients from group Ib had aortic dissection and in another three, an ascending aorta aneurysm developed. Reoperation was performed in six cases. No such complications occurred in group Ia. At 6 years, the proportion of patients free from complications related to the ascending aorta was 100% in group Ia vs 63 +/- 6% in group Ib (P less than 0.05). In group II, all the patients underwent aortic valve replacement. The modalities of repair of the ascending aorta differed with time.(ABSTRACT TRUNCATED AT 250 WORDS)