A statewide assessment of the compliance of surgical antibiotic prophylaxis (SAP) with guidelines was undertaken for large public hospitals in Victoria, Australia. This was carried out using data collected as part of a surveillance system for hospital-acquired infections. The study population comprised patients in Victorian public hospitals with >100 beds (N=27) undergoing cardiac surgical procedures, hip or knee arthroplasty, cholecystectomy, appendectomy, colon surgery or hysterectomy over a 21-month period. Australian guidelines recommend SAP for all 10 643 surgical procedures included in this study. Combining all procedures, 87% received SAP, the choice of antibiotic was concordant with guidelines for 53.3% of procedures, and the choice of antibiotic was considered to be 'adequate but not concordant' for 23.9% of procedures. SAP was considered to be inadequate for 18.9% of procedures. A large number of antibiotic regimens were utilized for cardiac and orthopaedic surgery. Documentation of timing of administration was not submitted for more than half of all procedures. Timing was concordant with guidelines for 76.4% of procedures when documented. Prophylactic antibiotic choice was generally more concordant with guidelines for cardiac and orthopaedic procedures than for other types of surgery. However, even for these procedures, where infections carry high morbidity, SAP was sometimes inadequate. Regular reporting on SAP compliance from data collected during surveillance for hospital-acquired infections is achievable. This should lead to improvements in both compliance and documentation.