BACKGROUND Postoperative spinal surgical site infection is a potentially frightful complication of posterior spinal surgery, unfortunately, it is quite a common complication. Posterior spinal surgeries could cause significant blood loss requiring blood transfusion. Though blood transfusion is an important common practice used in optimizing patient`s clinical condition when indicated, there is skepticism that it could be a risk factor for surgical site infection which is a dreaded complication of spinal surgery. There are a few studies in Western society that tried to determine association of surgical site infection and allogeneic blood transfusion. However, there are paucity of such studies in Nigeria, this informed the choice of the current study. OBJECTIVE To determine the incidence of postoperative surgical site infection and whether there is any association between perioperative allogeneic blood transfusion and postoperative surgical site infection in patients undergoing elective posterior spinal surgery. METHODOLOGY It was a prospective observational cohort study carried out in Memfys Hospital Enugu. Consenting patients who were 18 years and above admitted for open posterior spinal surgery were recruited into the study and were grouped into two groups of “Transfused” (those who had perioperative blood transfusion) and “Not Transfused” (those who did not have blood transfusion). Both groups were assessed for occurrence of postoperative SSI based on CDC criteria for diagnosis of SSI. Patients were followed up for 30 days (in cases of no implant use) and 90 days (in cases of implant use) for evidence of SSI. Data were collated and analyzed using Statistical Package for Social Sciences (SPSS) version 23. RESULT A total of 54 patients were recruited for this study, 27 subjects (50%) received blood transfusion and the other half did not receive blood transfusion. The overall mean age of the patients was 55.83±12.85 years. Lumbar spine was the most frequent region operated (46.2%), followed by cervical region (38.8%). There was no significant association between the region of surgery and blood transfusion (p = 0.635). The most frequent number of units of blood transfused per patient was two units among the Transfused patients. The overall incidence of SSI was 9.3%. The rate of SSI in the group that received blood transfusion (Transfused group) was 5.5% and the rate was 3.7% for those patients that did not receive blood transfusion (Not transfused). The occurrence of postoperative SSI in patients undergoing spinal surgery was not influenced by perioperative allogeneic blood transfusion (p = 0.639). In addition, there was no association between volume of blood transfused and surgical site infection (p = 0.843) in patients who developed SSI.