In this study the relationship between the presence or absence of organisms in bile or on closing wound swabs and the subsequent development of wound sepsis was confirmed. There was no significant difference in the incidence of septic complications among three treatment groups in which cefuroxime (iv) and ciprofloxacin (iv or oral) were administered. Consideration of costs attributable to the choice of antibiotic prophylaxis suggests that oral ciprofloxacin in biliary tract surgery may offer significant advantages.