To reduce the incidence of incisional hernia (IH) in colorectal surgery by implanting a mesh on the overlay position. The incidence of IH in colorectal surgery may be as high as 40%. IH causes severe health and cosmetic problems, and its repair increases health care costs. Randomized, controlled, prospective trial. Patients undergoing any colorectal procedure (both elective and emergency) through a midline laparotomy were divided into 2 groups. The abdomen was closed with an identical technique in both groups, except for the implantation of an overlay large-pore polypropylene mesh in the study group. Patients were followed up clinically and radiologically for 24 months. A total of 107 patients were included: 53 in the study group and 54 in the control group. Both groups were homogeneous, except for a higher incidence of diabetes in the mesh group. There were 20 emergency procedures in the study group and 17 in the control group. There were no statistical differences in surgical site infections, seromas, or mortality between the groups (33.3%, 13.8%, and 3.7% in the control group and 18.9%, 13.2%, and 3.8% in the study group). No mesh rejection was reported. The incidence of IH was 17 of 54 (31.5%) in the control group and 6 of 53 (11.3%) in the study group (P = 0.011). The incidence of IH is high in patients undergoing elective or emergency surgery for colorectal diseases. The addition of a prophylactic large-pore polypropylene mesh on the overlay position decreases the incidence of IH without adding morbidity.