Surgical site infections (SSIs) are a serious problem after abdominal surgery. This study aimed to compare closure of fascia with triclosan-coated monofilament polydioxanone (PDS) or standard PDS in decreasing the incidence of SSIs in patients who underwent abdominal surgery. In this randomized study, a total of 890 consecutive patients undergoing laparotomy for any gastrointestinal pathology were allocated to closure of the fascia with triclosan-coated PDS (treatment group; TG) or standard PDS (control group; CG). Patients were assessed every day during the hospital stay for SSIs and at the first, second, and fourth week after discharge. The surgical site was assessed in terms of superficial, deep incisional, or organ/site SSI. The main important finding was that SSIs were reduced as much as 24% by using triclosan-coated PDS. Surgical site infections occurred in 200 patients (22.4%), with 105 being early (in the first week) and 95 occurring late. Eighty five of the SSIs (19.1%) were noted in patients in the TG, whereas 115 of them (25.8%) were in the CG (p = 0.016). The infections were superficial in 126 patients, deep incisional in 48 patients, and organ/site in 26 patients. Most of patients (n = 651) had clean-contaminated sites. In subgroup analysis, SSI rates with triclosan-coated PDS were lower in clean, clean-contaminated, and contaminated incisions (0 in the TG versus 24.2% in the CG; p = 0.009; 13.6% in the TG versus 24.3% in the CG, p = 0.001; and 16.6% in the TG versus 27.8% in the CG; p < 0.0001, respectively). Closure of the fascia with triclosan-coated PDS decreased SSI rates as much as 24%. Also, SSIs were decreased significantly at clean, clean-contaminated, and contaminated sites. Therefore, triclosan-coated PDS might be recommended for fascial closure as a means of decreasing SSIs.