Background: Surgical site infection (SSI) is an infection that develops within 30 days after an operation or within one year if an implant was placed and the infection appears to be related to the surgery. It remains a major cause of morbidity and death. Objective: To determine the incidence of surgical site infections and microbial pattern at Kilimanjaro Christian Medical Center. Method: A prospective hospital based study conducted at KCMC general surgical wards from November, 2010 to March, 2011. A total of 263 newly operated inpatients under our services were enrolled but 27 patients among the group had lost on follow up visits and were removed from the study. So, only 236 patients completed the study’s one month follow up. Results: Two hundred and thirty six operated inpatients were followed up for the development of surgical site infection. Out 236 patients, 18 developed features of surgical site infection. Four patients had culture negative results. One patient who developed SSI due to an infected implant died. There were 142(60.2%) clean wounds, 69(29.2%) clean contaminated wounds, 8(3.4%) contaminated wounds and 17(7.2%) dirty wounds. Superficial SSIs constituted (61.1%) followed by deep (27.8%) and organ/space (11.1%) SSIs. The overall SSI rate was 7.6%. Clean, clean contaminated, contaminated and dirty wounds had infection rates of 3.5%, 8.7%, 25.4% and 29.4% respectively. There were 15 bacterial isolates; Staphylococcus aureus- 7 isolates, Klebsiella spp- 3 isolates, Escherichia coli- 2 isolates, Proteus spp-1 isolate, Coliforms- 1 isolate and Pseudomonas spp- 1 isolate. Of the seven staphylococcus aureus isolates, 6 were sensitive to Ceftriaxone. Gentamicin was found to be very potent against Klebsiella spp, E. coli, Proteus spp, Coliforms and pseudomonas spp. Multidrug resistance was also observed in a number of bacterial isolates. Conclusion: The incidence of surgical site infection at the centre is decreasing though it poses a great challenge in the management of surgical patients. Key words: Surgical site infection, clean wound, clean contaminated wound, contaminated wound, dirty wound.