AIMSThe objective of this study has been to evaluate, prospectively, to what extant the administration of antibiotics in surgical prophylaxis conforms with the established guide-lines laid down by the infections Comralilecs. MATERIAL AND METHODSAn incidence prospective multicontre study with a five weeks duration was carried out in 3 hospitals. All operated patients (n=562) were included with the exception of those from eye, ear, nose and throat surgery. A specially demgned form was used for data collection. The data used came from anesthesia and pharmacotherapeimc profiles.The valuation of prophylactic treatment was performed by a team of two pharmacists and one surgeon.hldication, antibiotic election, initiation and duration of prophylaxis were analyzed, RESULTSThirty-seven percent of 207 patients studied received antibiotic phrophylactic treatment Although there were differences betw-cn hospitals, an average of 40% of the antibiotic administered did not conform with the guide-lines established in each centre. The results "~ere 57%, 56% and 13% respectively. The adininistration of antibiotic phrophylaxis more than an hour before strutting surgery was the main inappropriate use (44%). CONCLUSIONSProspective studiesare useful for evaluating the use of antibiotics ill surgical prophylaxis. They enable the inclusion of a large number of patients and also an oblective measurement of the level of adherence to the Infection Comreattees recomanded guidu-lmes. This in turn determines wether or not corrective measures should be taken,