The aims of this study were to determine the clinical characteristics and outcome of patients who had definite infective endocarditis (IE) complicated by aortic ring abscess formation that was detected with transesophageal echocardiography (TEE) and to determine the prognostic significance of abscess formation in aortic valve IE. Patients who had aortic valve IE were selected from the International Collaboration on Endocarditis Merged Database (ICE-MD) if they underwent TEE. Among 311 patients who had definite aortic valve IE, 67 (22%) had periannular abscesses. They were more likely to have infection in the setting of a prosthetic valve (40% vs 19%, p <0.001) and coagulase-negative staphylococcal IE (18% vs 6%, p < 0.01) and less likely to have streptococcal IE than were patients who did not develop abscess (28% vs 46%, p = 0.01). Systemic embolization, central nervous system events, and heart failure did not differ between those who developed abscess and those who did not, but power was limited. Patients who had abscess were more likely to undergo surgery (84% vs 36%, p <0.001), and their in-hospital mortality rate was higher (19% vs 11%, p = 0.09). Multivariate analysis of prognostic factors of mortality in aortic IE identified age (odds ratio [OR] 1.6, 95% confidence interval [CI]1.2 to 2.1), Staphylococcus aureus (S. aureus) infection (OR 2.4, 95% CI 1.1 to 5.2), and heart failure (OR 2.9, 95% CI 1.4 to 6.1) as variables that were independently associated with increased risk of death. Periannular abscess formation showed a nonsignificant trend toward an increased risk of death (OR 1.9, 95% CI 0.9 to 3.8). Multivariate analysis of prognostic factors of mortality in complicated aortic IE with abscess formation identified S. aureus infection (OR 6.9, 95% CI 1.6 to 29.4) as independently associated with increased risk of death. In conclusion, in the current era of TEE and high use of surgical treatment, periannular abscess formation in aortic valve IE is not an independent risk factor for mortality. S. aureus infection is an independent prognostic factor for mortality in patients who have abscess formation.