Background: Surgical site infections (SSI) are the most common infection among surgical patients. SSI causes patient morbidity and mortality. Local nosocomial infection surveillance and prevention programs are reported to be highly cost effectiveObjectives: The main objective was to identify the incidence of SSI and its related risk factors. Other objectives were to identify the aetiological agents, their resistance pattern, and also to see if the rates of SSI would be influenced by feedback to the staff concerning both SSI rates found and observations concerning hygienic practices.Design and settings: A five-month prospective surveillance study of SSI, an indicator of healthcare quality, was conducted at the department of general surgery at KCMC, Tanzania. The study started 20th of July 2000 and ended the 20th of December 2000. SSI were classified according to Centers for Disease Control (CDC) criteria and identified by active bedside surveillance and post discharge follow up.Results: There were 396 operations on 388 patients included into this study. This study showed that 19.4% (77 patients) developed SSI. Twenty eight (36.4%) of these infections were apparent only after discharge from hospital. Another finding was that 87% of those whodeveloped SSI had received antibiotic prophylaxis. Significant risk factors for developing SSI during hospital stay were: operations classified as contaminated or dirty, operations lasting for more than 50 minutes, and longer preoperative stays. The only risk factor significantly associated with the development of SSI after discharge was having undergone a cleancontaminated operation. Staphylococcus aureus was the most frequently isolated microorganism, followed byEscherichia coli and Klebsiella spp. Most of the pathogens identified were multi-resistant, an exception being S. Aureus (54.5% of the isolates were sensitive to all the tested antibiotics).Conclusion: This study has shown that the incidence of SSI and the prevalence of antibiotic resistance in this teaching and tertiary level care hospital is high. The risk factors were similar to those reported in countries with more resources. Infection prevention measures should be re-evaluated.