The elucidation of the pathogenesis of postsurgical adhesion formation is still lacking. In this study experimental adhesion formation was studied in germfree (i.e. void of bacteria) and conventional rats (intestinal flora comprising over 400 species) using a caecal crush model. The germfree rats responded significantly weaker to the same stimuli, forming adhesions in only 20% of the cases as compared to the conventional rats 87.5% (p = 0.0076). The findings indicate that the bowel flora is of importance but not essential for postsurgical adhesion formation in rats.