BACKGROUND The incidence of bacteremia with organisms that may cause infective endocarditis after esophageal stricture dilation is unknown. There is disagreement among physicians regarding the need for antibiotic prophylaxis for patients with valvular heart disease undergoing dilation. Our aim was to determine the frequency and duration of bacteremia associated with esophageal stricture dilation. METHODS Blood cultures were obtained before and after stricture dilation in patients without valvular heart disease and in a control group of patients undergoing upper endoscopy without dilation. RESULTS A total of 103 patients undergoing dilation and 50 control patients were studied; 22 of 103 patients (21%) undergoing dilation had at least one post-procedure blood culture positive for viridans streptococcus, compared with 1 of 50 (2%) of control patients (p = 0. 001). Blood cultures obtained 1 minute after stricture dilation were positive for viridans streptococcus in 19 of 81 (23%), in 16 of 96 (17%) 5 minutes post-dilation, and in 3 of 63 (5%) 20 to 30 minutes post-dilation. Of the 19 patients with viridans streptococcus bacteremia 1 minute after dilation, cultures were still positive in 14 of 19 (74%) at 5 minutes and in 2 of 19 (10%) 20 to 30 minutes post-dilation. CONCLUSIONS These data support the use of antibiotic prophylaxis before esophageal stricture dilation for patients with valvular heart disease at risk for the development of infective endocarditis.