Background: Effective postoperative pain management is essential for the rehabilitation of the surgical patient. The PANSAID trial evaluates the analgesic effects and safety of the combination of paracetamol and ibuprofen. This paper describes in detail the statistical analysis plan for the primary publication to prevent outcome reporting bias and data-driven analysis results. Methods/design: The PANSAID trial is a multicentre, randomised, controlled, parallel, four-group clinical trial comparing the beneficial and harmful effects of different doses and combinations of paracetamol and ibuprofen in patients having total hip arthroplastic surgery. Patients, caregivers, physicians, investigators, and statisticians are blinded to the intervention. The two co-primary outcomes are 24-h consumption of morphine and proportion of patients with one or more serious adverse events within 90days after surgery. Secondary outcomes are pain scores during mobilisation and at rest at 6 and 24h postoperatively, and the proportion of patients with one or more adverse events within 24h postoperatively. Discussion: PANSAID will provide a large trial with low risk of bias regarding benefits and harms of the combination of paracetamol and ibuprofen used in a perioperative setting. Trial registration: ClinicalTrials.org identifier: NCT02571361. Registered on 7 October 2015.