In radical cystectomy (RC), surgical-site infection (SSI) remains one of the most frustrating postoperative complications. Only a few reports have assessed SSI after RC according to the guideline authorized by the Centers for Disease Control and Prevention (CDC guideline). In this study, using the guideline, we assessed the incidence, causative organisms, classification, and risk factors for SSI in patients receiving RC with urinary diversion (UD). The subjects of this study were 104 patients who underwent RC with UD at the Department of Urology, Sapporo Medical University Hospital, between January 1996 and December 2003. As prophylactic antimicrobial agents, intravenous cephalosporins or penicillins were started before surgery and maintained until postoperative day 3. Patients who had preoperative bacteriuria were treated with antimicrobial agents before operation to eradicate the bacteria or reduce their number. The CDC guideline was used for the diagnosis of SSI. The overall incidence of SSI was 33%. The most frequent type of SSI was superficial incisional infection (71%). Methicillin-resistant Staphylococcus aureus (MRSA) was the most frequently isolated organism, accounting for 38% of the causative organisms. Operation time was shown to be a significant risk factor for SSI. Preoperative antibacterial chemotherapy for bacteriuria was not sufficiently efficacious to decrease the incidence of SSI. In our study, the incidence of SSI after RC was 33%, although 71% of the infections were superficial. It is necessary to establish more appropriate countermeasures to prevent SSI after RC with UD; in particular, that caused by MRSA.