Antibiotic prophylaxis in clean surgery with implantation of prosthetic material is widely accepted, although there are no studies on its use in abdominal incisional hernia repair. The objective was to evaluate antibiotic chemoprophylaxis in incisional herniorrhaphy with the implantation of prosthetic material. A prospective non-randomized study (1990-1998) was conducted to analyse 216 patients undergoing surgery for abdominal incisional hernia who required a prosthesis (polypropylene) in the reconstruction and who met the criteria for clean surgery. Risk factors were observed in 31.5%, the most frequent being diabetes and obesity. The incisional hernia was located mostly in the abdominal midline and in 64.4% measured over 10 cm. Antibiotic prophylaxis was administered in 140 patients (64.8%) via the systemic route, the antibiotics being first- or second-generation cephalosporins or amoxicillin-clavulanic acid. Surgical wound infection occurred in 39 patients (18.1%), 19 who had received antibiotic prophylaxis (13.6%) and 20 who had not (26.3%). In multivariate analysis using logistic regression, the variables with statistical significance for local septic infection were antibiotic prophylaxis and number of risk factors. We can conclude therefore that antibiotic chemoprophylaxis is useful in abdominal incisional herniorrhaphy surgery with implantation of prosthetic material for reducing local septic complications.