In the present study the efficacy and safety of pefloxacin (400 mg/5 ml vial) intravenously administrated for surgical prophylaxis was assessed. Nine hundred and fifty-two patients were treated (599 M, 343 F), with a mean age of 57.9 years +/- 18.6 SD, and in all cases surgical prophylaxis was carried out according to the following scheme: short-term with 2 vials (800 mg) 1 h before the operation, repeated at 12 and 24 hours after the operation; long-term 2 vials (800 mg) 1 h before the operation repeated at 12 and 24 hours after the operation and followed by 1 vial every 12 h for other 2 days. The choice between the two schemes was conditioned by the type of operation and by the basic conditions of the patient. Pefloxacin was seen to be effective in preventing the onset of post-surgical infections (97%), also maintaining the clinical parameters considered within normal limits. Safety was also highly satisfactory, since only 22 (2.3%) cases of side effects occurred, particularly involving the gastro-intestinal system. Thus, in conclusion, the validity of pefloxacin in surgical prophylaxis, with special emphasis on its efficacy in elderly and compromised patients is asserted.