BACKGROUND Low-dose aspirin for the prevention of cardiovascular disease is recommended to be discontinued at least 7 days before spinal surgery. OBJECTIVE To determine the effect of stopping low-dose aspirin at least 7 days before surgery on the level of the perioperative blood loss or complications related to hemorrhage. METHODS Retrospective case study. METHODS Patients who underwent spinal fusion surgery for degenerative lumbar disease. METHODS Clinical outcome was measured by the Oswestry Disability Index. METHODS The aspirin group included 38 patients who had taken 100 mg aspirin for an average of 40.3 months. They stopped aspirin for at least 7 days before surgery (mean, 9.0 days). The control group included 38 patients who had not taken aspirin. Both groups were matched in terms of age, gender, number of fused segments, and surgical procedures. The diagnosis in all patients was degenerative spinal disease. RESULTS The mean age in the aspirin and control groups was 68.5 and 69.1 years, respectively. The mean number of levels fused was 2.0 segments in both groups. During surgery, the estimated blood loss was 855.3 cc in the aspirin group and 840.8 cc in the control group with no significant difference (p=.84). However, there was a significant difference in blood drainage after surgery. The hemovac blood drainage after surgery was 864.4 cc in the aspirin group but only 458.4 cc in the control group (p<.001). Therefore, the transfusion requirement after surgery was significantly greater in the aspirin group than in the control group (p=.03). The rate of complications related to hemorrhage was higher in the aspirin group than in the control group. CONCLUSIONS The intraoperative blood loss during spinal fusion surgery was similar in both groups. However, the blood drainage after surgery was significantly higher in the aspirin group despite stopping aspirin 7 days before surgery. Hence, surgeons should pay careful attention to postoperative blood loss and complications related to hemorrhage in patients who have been taking low-dose aspirin.