A Cochrane review (abstract , review ) included 17 studies with a total of 7 843 patients. All studies used a penicillin derivative or cephalosporin antibiotic. Overall infection rates were 3.1% and 4.5% in the prophylaxis and control groups, respectively (OR 0.64, 95% CI 0.50 to 0.85). The subgroup of patients with herniorrhaphy had infection rates of 3.5% and 4.9% in the prophylaxis and control groups, respectively (OR 0.71, 95% CI 0.51 to 1.00). The subgroup of patients with hernioplasty had infection rates of 2.4% and 4.2% in the prophylaxis and control groups, respectively (OR 0.56, 95% CI 0.38 to 0.81).