Anastomotic leakage is the most important complication leading to morbidity and mortality in colorectal surgery. To prevent anastomotic leakage, a number of drugs with different mechanisms of action were tested, and autogenic grafts and various synthetic materials were used for reinforcement of the anastomotic region. In this experimental study aimed at preventing anastomotic leakage and dehiscence, we used dehydrated, lyophilized human dura mater and free peritoneal graft for reinforcement of anastomotic region after primary repair in rats, and investigated whether they are superior to primary anastomosis. The rats were sacrificed 3 and 7 days postoperatively. The anastomotic region was observed macroscopically for adhesions, bursting pressure of bowel was measured for tensile strength of the anastomosis, and histopathologic evaluation was performed for anastomotic healing. Compared to the control group, dura mater and free peritoneal graft groups displayed a lower bowel bursting pressure (p < .05), worse anastomotic healing (P < .05), a higher number of adhesions, and presence of anastomotic stricture. In conclusion, both human dura mater and free peritoneal graft reinforcement groups had worse anastomosis healing. The results could be attributed to avascularity of grafts and to aggravated adhesions between anastomosis and intra-abdominal organs, which created a favorable environment for reproduction and dispersion of bacteria and consequently led to decreased anastomosis healing.