Sir, The effectiveness of antibiotic prophylaxis in low-risk patients remains a matter of investigation, since it is well known that antibiotic prophylaxis can be associated with adverse drug events1 (e.g. haemolytic anaemia after proper administration of just one dose of cephalosporin prophylaxis2). Randomized controlled trials (RCTs) are widely accepted to be the most reliable method for determining the efficacy of an intervention; however, methodological limitations have been expressed in terms of safety assessment.3 The aim of this systematic review was to describe the methodology of safety evaluation in RCTs concerning antibiotic prophylaxis in hernia and breast surgeries and in laparoscopic cholecystectomy (LC). PubMed, Scopus, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, ACP Journal Club, Database of Abstracts of Reviews of Effects, Science Citation Index Expanded and Google Scholar were searched in order to identify articles assessing the effectiveness of systemic antibiotic prophylaxis versus placebo in hernia surgery, breast surgery and LC. An electronic search was performed from 1995 … [introduction]