A comparative study was performed on the efficacy, safety and tolerability of three different antibiotics (imipenem, ceftazidime, ceftriaxone) in the prevention of postoperative infection. Evaluations were made on the basis of the results obtained in a group of 90 patients subdivided into three matched groups each of which was treated with one of the three compounds. The trend of cutaneous temperature showed differences at the limit of significance (p congruent to 0.05). Variations in leucocyte concentrations showed an analogous pattern in all patients, although there were fewer and with a shorter duration in subjects treated with imipenem. The wound healing process was improved in patients receiving prophylactic antibiotic treatment in the form of imipenem (0.01 < p < 0.05) who also showed a greater respect for therapeutic protocols (80%), a higher percentage of remission of fever and a shorter mean hospital stay (9 days). In the light of these preliminary results the authors express their favourable judgement regarding the choice of imipenem for the prophylaxis of postoperative infection; however, each of the three protocols showed a considerable prophylactic capacity as well as good tolerability and ease of use.