Objective: Postoperative inflammation and infections are common complications of spinal surgery and have similar symptoms. However, postoperative infection may lead to a poor outcome and must be differentiated from postoperative inflammation. The objective of this study is determine the changing pattern of postoperative ESR and WBC counts, and investigate the effects of different variables. Methods: A total of 61 patients who underwent spinal surgery were enrolled in this prospective study. The erythrocyte sedimentation rate (ESR) and white blood cell (WBC) counts were measured the day before surgery and on 1st, 3rd, 5th, 7th, and 14th postoperative days. Results: WBC counts increased on the 1st postoperative day in comparison with the preoperative day (p<0.001), and they gradually decreased until the preoperative value was reached on the 14th postoperative day (p=0.14). The ESR also increased postoperatively, reaching a peak on the 5th postoperative day in comparison with the preoperative day (p<0.001) and gradually decreased thereafter. However, on the 14th postoperative day, the ESR was significantly greater than the preoperative value (p<0.001). In addition, a significant positive correlation was observed between ESR and age, duration of surgery, intraoperative blood loss, and duration of anesthesia. Conclusion WBC count continued to rise and was the highest on the 1st postoperative day, after which it gradually decreased and attained normal values on the 14th postoperative day, while the ESR increased on the 1st postoperative day, reached the highest level in patients with and without simultaneous instrumentation on 7th and 5th postoperative days, respectively, and gradually decreased.