Fifty cases of aortic valve endocarditis during a 6-year period between 1982 and 1988 were reviewed. Twenty-three (46%) had aortic root complications by way of aortic root abscess or mycotic aneurysm in the perivalvular area. Patients with root complications were grouped into the aortic root abscess (ARA) group and those without into a non root abscess (NARA) group. Prosthetic valve endocarditis dominated in the ARA group (12 and four cases of prosthetic valve infection in the ARA and NARA groups, respectively; P less than 0.01). Surgical mortality was significantly higher at 13.6% in the ARA group as opposed to 2.2% in the NARA group (P less than 0.05). Post-operative aortic regurgitation was present in 8 (57%) of 14 patients in the ARA group surviving surgery but in only two (8.7%) of 23 patients in the NARA group (P less than 0.03). We conclude that aortic root complications are a frequent occurrence in aortic valve endocarditis, lead to an increased operative mortality and is associated with a high incidence of post-operative aortic regurgitation.