The incidence of fecal streptococci in bile is between 5 and 15 per cent of all positive culture findings. Fecal streptococci are not susceptible to the aminoglycoside or cephalosporin antibiotics, although these drugs are widely favored for prophylaxis during surgical treatment of the biliary tract. Over a three year period, 64 episodes of bacteremia have been identified in patients undergoing treatment for obstructive jaundice. Fifteen (23 per cent) of these episodes were due to fecal streptococci. The implications of this finding are discussed and the role of acylureidopenicillin antibiotics for prophylaxis considered.