Background In order to survey the bacterial flora in patients with uncomplicated gallstone disease and cholecystitis, we have taken bacterial cultures from the bile of all patients undergoing cholecystectomy at one surgical unit.Methods Cultures were taken according to standardised routines from the bile during all cholecystecomies performed at the department of surgery, Enköping hospital, Sweden, April 2007 to February 2008. Use of antibiotics within 3 months prior to surgery, indication for surgery, prophylactic antibiotics and postoperative complications were registered prospectively.Results Altogether 136 procedures were performed during the period of study, including 83 (61%) in women. Mean age was 51 years, standard deviation 16 years. Bacterial growth was seen in 21 (15%) of the cultures, including Streptococcus species other than Enterococcus (n=6), Enterococci (N=2), Clostridium perfringens (N=1), Enterobacter (n=1), Escherichia coli (n=5), Klebsiella (n=1), Coagulase-negative Staphylococci (n=2) and mixed flora (n=3). Mean age was 18 years higher for patient with positive culture than those with negative (p<0.001). This difference remained significant even if patient operated for cholecystitis were excluded (p<0.003). There was no significant difference between men and women. In 34 (25%) cases the procedure was done for acute cholecystitis. Antibiotics were given to 11 (8%) of the patients. The culture was positive in 12 (35%) of the patients undergoing surgery for cholecystitis (p<0.001). Postoperative infectious complications were seen in 12 (9%) of the patients. In multivariate logistic analysis, neither positive culture, ongoing or previous cholecystitis or prophylactic treatment with antibiotics was significantly associated with the risk of postoperative infectious complications.Discussion Bacterial growth in the bile is more common in elderly, even in the absence of cholecystitis. Positive culture was seen in one third of the patients undergoing surgery for cholecystitis. No individual factor was associated with an increased risk of postoperative infectious complications.