Background: Use of meperidine for the treatment of post-anesthetic shivering (PS) after neuraxial opioids is limited by risk of respiratory depression. Objective: To compare the efficacy of tramadol, nalbuphine, ondansetron and a placebo in the treatment of PS after spinal anesthesia in cesarean section patients. Methods: Two hundred eighty parturients who developed moderate to severe shivering and required treatment after cesarean delivery under spinal anesthesia with bupivacaine and intrathecal morphine 0.2 mg were randomized into 4 groups. Group T, Group N, Group O and Group P were given tramadol 0.5 mg/kg, nalbuphine 0.05 mg/kg, ondansetron 0.1 mg/kg and normal saline 5 mL IV, respectively. The patients were evaluated at 15 minutes after treatment and were observed for a recurrence of PS within 4 hours in a double-blinded fashion. Results: The treatment success rate (no or mild shivering) of PS in groups T, N, O and P were 88, 81, 61 and 36 %, respectively (p<0.001). The treatment success rate of groups T vs P, N vs P, O vs P, T vs O and N vs O were significantly different (p<0.001, 0.001, 0.003, <0.001, and 0.009, respectively). The success rate between groups T vs N was not significantly different (p=0.223). Recurrence rate of PS in groups T, N, O and P were 14 %, 15 %, 11 % and 28 %; p=0.329. Other side effects such as pruritus, nausea/vomiting, and dizziness were few and treatable. Conclusion: Tramadol, nalbuphine and ondansetron were efficacious in the treatment of PS after intrathecal morphine in cesarean section patients with low recurrence rates. Tramadol and nalbuphine were superior to ondansetron in the treatment of PS.