Introduction: Postcesarean section pain management is important for both the mother and the newborn. This study compared the analgesic effects and incidence of adverse events associated with intravenous patient-controlled analgesia (iv-PCA), using different sufentanil-tramadol combinations for postoperative pain control. Methods: Parturients (n=5,794) who had been scheduled for cesarean section under neuraxial anesthesia and had received iv-PCA between September 2013 and March 2017 were retrospectively analyzed. These patients were assigned to three groups, based on different sufentanil-tramadol combinations: ST1 (n=1,347), ST2 (n=2,401), and ST3 (n=2,046). The analgesic efficacy, total drug consumption, and incidence of adverse effects within 24 hours after surgery were compared among the three groups. Results: The ST3 group had lower visual analog scale pain scores at rest and with movement at all time points during the first 24 hours postoperatively than the other two groups (P<0.01, Bonferroni corrected). The sufentanil dosage administered to the ST3 group was lower, and the tramadol dosage was higher than those administered to the other groups within 24 hours after surgery (P<0.01, Bonferroni corrected). Moreover, all parturients scored 2 points on the Ramsay sedation scale. Adverse reactions such as pruritus and respiratory depression were not observed in any group. No significant differences were noted in the incidence of nausea/vomiting, abdominal distension, and dizziness among the three groups (P>0.05). Conclusion: The visual analog scale scores for postoperative pain decreased as the concentrations of sufentanil and tramadol administered in iv-PCA moderately increased over 24 hours after surgery. This analgesic strategy resulted in a significant reduction in the total sufentanil requirement without increasing the incidence of adverse effects.