The aim of this study was to evaluate bacterial flora infecting during the surgical procedures the peritoneal cavity and drains which were used after the surgery in 40 patients who underwent surgery for colon and rectum tumors. Smears from the peritoneal cavity, liquid removed from the drain taken at 3-4 days after the surgery and smears from the drain taken at the end of drainage of each patient were examined for bacterial content. The comparison of bacterial flora found in the peritoneal cavity with bacteria found in drains showed that the frequency of isolation of anaerobes decreased in contrast to aerobes which were more often cultured over the time of drainage (p

Keywords: bacterial flora, Drainage, Surgery, tumor