Abstract Background and aims The present randomized open label parallel group study was conducted to evaluate if an oral oxycodone (OXY) regimen can be at least equally effective and as safe for postoperative analgesia after caesarean section (CS) as a standard of care program using nurse-administered intravenous morphine (IVM), followed by oral codeine. Methods Eighty women (40 + 40) were scheduled for elective CS under spinal anaesthesia. All patients received postoperative multimodal analgesic therapy, including ibuprofen and paracetamol. The OXY group got standardized extended release and short acting oral treatment (and in a few cases intravenous OXY) as needed and the other group received current standard of care, IVM as needed for 24 h, followed by codeine. Opioid treatment lasted maximum five days. Outcome measures were pain intensity (numerical rating scale, NRS), opioid requirements, duration of administering opioids and safety for mother and newborn. All opioids in the study were expressed in OXY equivalents, using a conversion table. As the bioavailability of each opioid has a certain extent of interindividual bioavailability this conversion represents an approximation. The possible influence of opioids on the newborns was evaluated by the Neurological Adaptive Capacity Score at birth and at 24 and 48 h. Results During the first 24 h, there were no differences between treatments in opioid requirements or mean pain intensity at rest but pain intensity when asking for rescue medication was lower in the OXY than in the IVM group (mean ± SD; 5.41 ± 6.42 vs. 6.42 ± 1.61; p = 0.027). Provoked pain (uterus palpation) during the first 6h was also less in the OXY group (3.26 ± 2.13 vs. 4.60 ± 2.10; p = 0.007). During the 25–48 h period postoperatively, patients on OXY reported significantly lower pain intensity at rest (2.9 ± 1.9 vs. 3.8 ± 1.8; p = 0.039) and consumed less opioids (OXY equivalents; mg) (31.5 ± 9.6 vs. 38.2 ± 38.2; p = 0.001) than those on IVM/codeine. The total amount of opioids 0–5 days postoperatively was significantly lower in the OXY than in the IVM/codeine group (108.7 ± 37.6 vs. 138.2 ± 45.1; p = 0.002). Duration of administering opioids was significantly shorter in the OXY group. Time to first spontaneous bowel movement was shorter in the OXY group compared with the IVM/codeine group. No serious adverse events were recorded in the mothers but the total number of common opioid adverse effects was higher among women on IVM/codeine than among those receiving OXY (15 vs. 3; p = 0.007). No adverse outcomes in the newborns related to treatment were observed in either group. Conclusions In a multimodal protocol for postoperative analgesia after CS better pain control and lower opioid intake was observed in patients receiving oral OXY as compared to those on IVM/codeine. No safety risks for mother and child were identified with either protocol. Implications Our findings support the view that use of oral OXY is a simple, effective and time saving treatment for postoperative pain after CS.