From 1992 to 1999, 713 total joint arthroplasties were performed in The Department of Orthopaedic Surgery, The University of Hong Kong. Since January 1993, a uniform prophylactic antibiotic regime was employed: one dose of first generation cephalosporin (one gram cephazonlin) on induction and every 4-hourly. In case of sequential bilateral total knee arthroplasty, one gram of cephazolin will be given on induction for the first knee and one hour before the operation on the opposite knee. Antibiotic will be discontinued post-operatively. No significant difference was identified between the infection rate before (1.4%) and after (1.2%) the adoption of the prophylactic antibiotic guidelines (p > 0.4). The study had shown that one dose of first generation cephalosporin is as effective as multiple dose of prophylactic antibiotic, either first or second generation cephalosporin, in preventing infection in total joint arthroplasty.