Three principles must be followed to maximize the benefits of antimicrobial prophylaxis (AMP): 1) use an AMP agent that is bactericidal with a spectrum that covers the most probable intraoperative contaminants; 2) the initial dose of AMP agents should be given no more than 30 min before the skin is incised: and 3) maintain effective levels of antibiotics throughout the surgery and until at most a few hours after the incision is closed in the operating room. These recommendations have become standardized in North America and Europe. A few controversies, however, persist in Japan, especially concerning the duration of AMP. Most practitioners recommend that prophylaxis be continued until postoperative day 3 to 4. However, some authors reported that the administration of AMP agents for 3 to 4 days causes the development of resistant strains. It is thus necessary to formulate national guidelines for appropriate AMP which are validated by the results of randomized, controlled trials conducted in Japan. In the treatment of postoperative infections, Gram-stain-based antibiotic selection is necessary and full knowledge of the interrelationships between pharmacokinetics and pharmacodynamics is important for determining effective regimens. The time that serum levels exceed the minimum inhibitory concentration is the most significant parameter determining the efficacy of beta-lactams, whereas the log area under the curve and peak serum level are the major parameters for aminoglycosides and new quinolones, respectively. Careful application of these concepts should allow surgeons to use more optimal dosing regimens in Japan.