Background: development of new multimodal analgesic regimens have led to substantial improvement in postoperative pain relief. Aim of the work: we designed this study to compare the effect of combined vitamin B complex-gabapentin versus gabapentin alone on postoperative pain in orthopedic surgery under spinal anesthesia. Methods: 80 patients who underwent elective orthopedic surgery under spinal anesthesia were randomized to receive orally 300 mg gabapentin (Group G) or 300 mg of gabapentin plus 2 vitamin B complex (Group GB) tablets 30 minutes before surgery. Postoperative pain intensity and total analgesic consumption during 12 hours after surgery, vomiting, and drowsiness during recovery were assessed. Results: the pain intensity in the gabapentin plus vitamin B complex group was lower than gabapentin group during 12 hours after surgery (p-value <0.001). Meanwhile, the total analgesic consumption in this group was less than gabapentin alone(p-value <0.05). The incidence of vomiting in patients who received combined gabapentin—vitamin B complex group was similar to gabapentin alone (p-value >0.05). Conclusion: the combination of vitamin B complex to gabapentin reduced intensity of postoperative pain and also the total amount of analgesic consumption within the first 12 hours postoperative following orthopedic surgery under spinal anesthesia.