Inflammatory bowel disease may have a deleterious effect on bowel healing, but its role is difficult to demonstrate in clinical practice because of the association of multiple factors. An experiment was conducted in rats. They were divided into two groups: group I, a model of acetic acid induced colitis, and group II, the control group. Both groups underwent a rectal resection and primary anastomosis. On postoperative day 7, the bursting strength of the anastomosis was evaluated. There were 44 rats in group I and 38 in group II. In 91% of group I rats there were histopathological changes compatible with inflammatory bowel disease (IBD). Mean bursting pressure was significantly reduced in rats with acetic-acid induced IBD (142.18 +/- 18.22 mm Hg in group I, and 208.85 +/- 14.8 mm Hg in group II; p < .05). These results suggest the deleterious effect of IBD on bowel healing.