The authors have reviewed 40 prospective studies of bacteremia with gastrointestinal procedures. Endoscopic procedures with a low mean frequency of bacteremia were esophagogastroduodenoscopy (4.2%), endoscopic retrograde cholangiopancreatography (5.6%), colonoscopy (2.2%), and sigmoidoscopy (4.9%). A higher mean frequency of bacteremia was encountered with esophageal dilation (45%) and variceal sclerotherapy (31%), although the number of patients studied was small. Potentially pathogenic organisms, such as Streptococcus viridans, Staphylococcus aureus, and Staphylococcus epidermidis have been isolated. Recommendations for antibiotic prophylaxis are reviewed. Less cumbersome regimens encourage compliance and are preferred.