Introduction: Incidence of surgical infection is greater among elderly patients undergoing surgery than among the general population, with a serious compromise regarding morbidity and mortality in this group of patients with increased risk., Aim of the Study: To determine the microbiological features of surgical infections in patients over 65 years of age compared with those younger than 65., Patients and Methods: Over the past 2 years, 2,064 patients underwent surgery in our Department. One thousand three hundred sixty seven of those patients (66.7%) had 65 years of age or less and 688 (33.3%) were over 65. Patient characteristics regarding the type of surgery (degree of contamination) and the nature and type of the condition requiring surgery are reported. One hundred five hundred sixty two samples were submitted for microbiological study. The microbiological infectious pathogens and their characteristics were determined. The Chi-square test was used for the analysis of potential differences related to the age of the patient., Results: The rate of samples sent for microbiological study is higher among patients over 65. In addition, these patients show both quantitative and qualitative differences in their infectious microbiological spectrum, mainly in clean-contaminated, contaminated and dirty surgical procedures. Fungal infections play a significant role in this group of patients., Conclusions: Facultative gram-negative bacilli, aerobic gram-positive cocci, and fungi are the main pathogens responsible of surgical infections in elderly patients, compared to all other patients, thus requiring specific antibiotic prophylactic and therapeutic regimes.