Bacteremia after esophagogastroduodenoscopy and endoscopic procedures such as esophageal variceal sclerotherapy is well recognized. The theoretical risk of endocarditis has led the American Heart Association and other authorities to recommend antibiotic prophylaxis for these procedures. However, no well-documented episodes of endocarditis associated with endoscopy have been reported. The current case of prosthetic valvular endocarditis is clearly linked to endoscopic sclerotherapy and occurred despite such antibiotic administration. This failure of prophylaxis may be due to factors specific to this patient; however, the efficacy of prophylaxis remains to be proven.