Objective : To study the adherence to local hospital guidelines for antimicrobial prophylaxis in surgery, and explore reasons for non-adherence. Methods : A prospective, multicentre audit of elective procedures, without prior suspicion of infection, was carried out in 13 Dutch hospitals. By reviewing medical, anaesthetic and nursing records, and medication charts, the prescription of antibiotics was compared with the local hospital guideline on antibiotic choice, duration of prophylaxis, dose, dosing interval and timing of the first dose. Results : Between January 2000 and January 2001, 1763 procedures were studied. Antibiotic choice, duration, dose, dosing interval and timing of the first dose were concordant with the hospital guideline in 92%, 82%, 89%, 43% and 50%, respectively. Overall adherence to all aspects of the guideline, however, was achieved in only 28%. The most important barriers to local guideline adherence were lack of awareness due to ineffective distribution of the most recent version of the guidelines, lack of agreement by surgeons with the local hospital guidelines, and environmental factors, such as organizational constraints in the surgical suite and in the ward. Conclusion : This study shows that, although adherence to separate aspects of local hospital guidelines for surgical prophylaxis in the Netherlands is favourable, overall adherence to all parameters is hard to achieve. Adherence to guidelines on dosing interval and timing needs improvement, in particular. To increase the quality of antimicrobial prophylaxis in surgery, effort should be put into developing guidelines acceptable to surgeons, in adequately distributing the guidelines and to facilitating logistics. Audits of surgical prophylaxis may help hospitals identify barriers to guideline adherence.